My first foray into big-blocks, here's what I'm building: 67 SS clone, 468 4-bolt early eighties Suburban block, 10:1 compression with iron 990 heads, 120cc chambers, big valves, comp 280H, .520-.520 lift, 230*-230* @.050 lift. 110*lsa, Performer RPM intake, 1413 Edelbrock 800cfm vac secondaries, GM HEI distributor, stock iron manifolds, dual 2 1/2 magnaflows to stock rear wheel exits. Th400 trans w/2500 stall verter, and 3.36 rear gears in a 10 bolt rear. I know this is probably a goofy mix of stuff, but 6000 is my intended max rpm, I don't intend to race the car, and I'm not looking to extract every HP I can find. The car will be an occasional car show and weekend driver. Any ideas on horsepower/torque numbers for this combo and how streetable the rectangle port heads are? Can somebody advise forged or eutectic pistons for my application, recommend a brand, and how important is balancing the new rotating assembly? Also will the 10 bolt hold up? Thanks for your help.

Not a good combo. Those 990 heads are not good for the street, yet don't pull good enough at high rpms. A good set of large early ovals would do you much better. Throw those factory exhaust manifolds in the trash and get a set of 1.75 headers. Re-curve your distributor and you will bein the ballpark. I would suggest staying away from hyper pistons, they turn into grenades when they let go. I like SRP pistons, made by JE, but for a relatively low rpm application TRWs are ok too, just tremendously heavy.

You'll probably be looking at 350 HP at the rear wheels, lotsa cam sound , and an animal to drive without the power to back it up. For now it will work and run, just not make th numbers you're hoping for.

Devin

thats really not that big of a cam for that many cubes I have the same cam in my motor, and had it in my other 454. And for the low rpm range the rectangles are hurting you. a set of ovals would be ideal

The Rectangle heads will work with a 454, ovals would work a bit better for low-end and midrange power. Thousands and thousands of cars built with rect port heads.

Ben's 454HO with stock small roller cam and the factory Rect port heads, 12.9 something at 105 or 106

On 'FourEightNine' BrIan's 454, his 9:1 engine with that '280 Magnum' cam went 12.05 at 109mph (4.56, slicks, and 3500 stall), closed chamber oval port heads with a botched install of larger 1.88 ext valves

I do believe a 'small cam' like that Magnum may actually be close to what you need. This is to say, wake-up that big sleepy intake port. OTOH, just like the 454HO, just when the RPMs get going, the RECT ports start working for you, the smaller cams run outa juice....Brian reported best times shifting at 5000 rpm

Hyper E pistons are good but you must watch your total adv. Ask "Brettd85" about Hyper E pistons coming apart when the adv gets a bit outa hand with pump gas.

Let me think some more about your engine combo but you are looking at something in the 425 horse/500 ft lbs torque with headers.

Yes, a 10-bolt will live forever unless you do burnouts all the time to impress your friends.
Another quick way to blow the 10-bolt is to throw some slick on it, 3500 stall and trans brake launches.

edit:
If just cruizin,,,,no need to change. Once you get whupped, you'll wanna change. Got posi in that 10-bolt?

Still thinking about some cams to work with your CR and Rect port heads.
The factory street mechanical LS-6 cam does come to mind.......

Thanks for the info. I guess I'm more into restoration, I'm trying to maintain something close to stock under-hood look. That's the reason for OEM manifolds, plus they move underhood heat more effectively, and they don't produce that thin header exhaust note. Haven't purchased pistons yet, I had set 10:1 CR as my target to run on 93 octane pump gas. As I said, the car won't see the track, just want a nice weekend cruiser. I'm too danged old to care anymore about burnouts, I'll probably hang with the open 10-bolt till I can find an affordable '67 12-bolt for it. I've always run SBC's until now, so I welcome your BB input.