Sorry for the lengthy post. I am picking up a 72 Chevelle on Saturday and have been researching a lot on this site and others in anticipation of getting it. I’m wondering if you guys can help me figure out what exactly I have here. I had a 71 about 12 years ago and am a bit out of touch with all of this stuff. Here's what I know about the setup:

-1975 350 block bored .030 over
-Cast crank (polished)
-Rods (shot peened??)
-Holley 750 w/ mech secondaries
-Weiand single plane intake (looks like maybe an X-cellerator?)
-Heads are 64cc chambers w/ 1.95/1.50 valves (the guy says they're "camelback" heads - I'll be checking the casting numbers when I get the car to see for sure what they are.) I'm also told there were hard seats (what are these?) installed on the exh valves and new seals – both done when the engine was built.
-Forged flat top pistons TRW 2256F (he said about 9.5 or 10 to 1 compression- does that sound right?)
-A customer ground Howard’s cam:
Int duration 230deg @ .050" lift .480
Exh duration 237deg @ .050" lift .491
Lobe Separation 108deg
Intake Center Line 104deg
-"high rev" lifters (???)
-Balanced
-Some HEI distributor (I didn’t look closely at it when viewing the car – it’s blue)
-1 1/2 inch headers.
-TH350 w/ shift kit and 2500 stall
-Ladder Bars
-4.56 gears (ouch)

The engine was just rebuilt in November by an engine shop in Minneapolis and there is around 100 miles on it, so it’s still in the break-in stage. The TH350 was also rebuilt in Novemeber. Any thoughts on how all this will work together? I do understand the gears are a little over the top for the rest of the setup. Any help would be greatly appreciated. Thanks in advance for helping a newbie!

Disclaimer: I'm just a rookie with enough knowledge to be dangerous, lol. Not a pro here.

Compression ratio should be between 9.6:1 with a thick gasket to 10.3:1 with the thinnest gasket I know of.

The intake manifold I'm not sure about. Typically a combo like this uses a high rise dual plane rather than a single but I'm not sure if the 4.56 gears will make good use of the single plane.

The cam looks like it'll be pretty rumpity. Might be a tad to big but probably not, looks okay, I think.

The hardened exhaust seats are used so that old heads can be used with modern unleaded fuels. Sometimes heads with "soft" seats don't work out so well with unleaded.

Shot-peened rods means they were stressed relieved. Shot-peening makes the rod more dense and thus stronger, if I remember correctly.

Not sure what is meant by hi-rev lifters. Probably bleed down faster than normal hydraulics or are made lighter in some other way?

Not sure if the headers are big enough, you'd have to ask someone that knows more than I do.

I think you could use more stall on the converter. But again, you'll have to ask someone with more xperience.

HEI should be fine if it has good parts.

Cast crank might not like the high-rpms your car might run, but some say they can take it just fine.

Its not bad but could use a little work. As for the manifold and carb, definitely a dual plane intake is right. Id get rid of the single plane and put a performer rpm intake in there. Typically a vacuum secondary carb is nicer for street use, but that doesnt mean that a mechanical secondary wont work so try it out and see how you like it. Although the gears do sound like a bit much(more like 4.11 gears at most), the converter is probably a little mild. That cam(even though Im not positive) would probably like a 3000+ converter to do best. Also, the mild converter may or may not cause the engine to bog or stumble a tad with the double pumper carb. Thats because the secondaries hit "right now" when you hit the gas, but the mild converter grabs good at lower rpm. A bit more of a converter can alleviate this issue(if its there). But its less of an issue cause the converter isnt so far off that its worthless to keep, so Id keep it, get a better matched gear, and see how the carb you have now works out for you.

Those cam specs arent familiar to me, so I cant guess which one it probably is for sure, but roughly 10:1 compression sounds about right for a camshaft like that. Im not sure about the specs on those pistons, so I wont try and make a guess just yet where your compression should actually be. Ill do some lookin around for those pistons, but I would guess that the estimates you were given are close and thats a good thing(hopefully its close). Its not terrible, but at the same time, there is some stuff that is mis matched a bit.

The first thing you should do is become a member of the Northstar Chevelle Club. Based in MN and the Prez of the club lives in your area.
Who built the engine, most members know local builders and their markings.
Who was the previous owner, that will also help find info needed. You can email me or hunt for Derek69SS on the forum (the Prez) Guys in the club are happy to help and a club meeting is coming up soon.

Thanks, everyone, for your thorough replies. I guess I won't really be able to tell how it will work until I actually get to try it out. I did take it for a drive before I bought it (of course), but with so few miles on the engine I was very light on the throttle. How many miles do you all suggest I go before really getting on it?

daveseitz - I sent you a PM.