I'm using a stock-style 3 row with a clutch fan, and have no cooling problems. It's the same one that was spec'd for a 327/clutch in the rad shop's reference materials.
My rat is sitting on SBC frame stands. The Milodon 7-quart kickout style pan is a little close to the crossmember, but does not hit it.
Putting a rat where a mouse lived may not drop the ride height at rest much, but when you cross an intersection dip or go over a speed bump you will probably wish you had stiffer springs (at the least). The SB springs just can't do well with the dynamic (in motion) loads put upon the front end, even though they appear to hold up the car well in the driveway.
In my '66, a BBC with long water pump and clutch fan and 3-core radiator puts the fan very close to the radiator itself. There is hardly room to pull a fan belt between the fins and the fan.
On the other hand, I have absolutely zero cooling problems, and do not need a shroud.
I built one from .050" aluminum, but it acts more as a finger guard, since the proximity of the fan to the rad promotes great flow.
If I had chosen a short water pump setup, this might all have turned out differently.
Also, my engine compartment is vented very well, so even in traffic on a 100-degree day, there is no overheating from soak or trapped heat.
Headers on the '66 are a tight fit for 2" under chassis style. A couple of spots rubbed the frame, and a driver side primary tube just kisses the steering shaft unless you ding it a little bit.
These would be Hooker #2455 or 2217s. Hope I got those numbers correct !!
I yanked the same headers that were in my BBC 2nd gen Camaro, and they fit right into the Chevelle setup. I think this is the same deal for the '68-'72s.
These headers hang down with a fair amount of room between them and the underside of the floor. There is plenty of ground clearance to be gained here for a lowered car. At least a full inch, which makes a big difference when you are just skiffing speed bumps and lousy driveways (like the one they have at Classic Industries).
A tall intake (such as an air-gap or Victor) + a tall air filter definitely will not fit under the flat hood of my '66.
I'm running pass-side alternator, and the p/s is from an '80 Camaro. The mount is standard GM, although I customized it at the side of the road a few months back (@@!!@@) when I had no choice. Those pictures are still on the site here, likely, since I didn't cancel them.
With the Milodon pan, I cannot pull the engine+trans together. I have to yank the trans, McLeod scattershield, clutch, and flywheel, then helicopter the engine straight up. This is due to the little clearance left between pan and crossmember.
On that issue, I noted a while back in Hot Rod Magazine which ran a multiple crate-motor test using (I think) a '69 Chevelle, that they had whacked the stock crossmember for a welded tubular one, and gained a great deal of room.
I really would like to see and hear more about that. I'd do it if I could be assured of equal or better strength.
I had to use a 7" dual-diaphragm brake booster due to lack of clearance between the larger diameter ones and my fabbed valve covers (large, to clear rollers and a girdle). The normal stock Chev v/c height should allow at least an 8" booster, or better a 9" one. That is what I had at first when I had just stuffed in the rat with a stock bellhousing and Super T-10.
I plan to raise my engine up by about 3/8ths of an inch using motor mount spacers. I will make them from aluminum plate.
The reason for this is two-fold:
1. Increase clearance between the crossmember and the large Milodon pan.
2. Gain some extra ground clearance for the Hooker 2"x 3.5" headers.
Of course, raising the engine will require also raising the trans, and re-adusting the pinion angle of the rear end. I could leave the trans where it is and just increase the angle of the engine, but that would just put more stress on the u-joint, in my reasoning. I could be wrong, though.
Raising the rat motor is not normally a good idea, due to c/g considerations. However in my case most of the engine is aluminum, the battery is gone, the hood is race-weight 'glass, and other weight-saving measures have been taken. I don't foresee any increase in tendency to roll, since it is not an iron engine.
I recommend increasing the front sway bar to at least 1-1/8th dia. Many people run 1-1/4, or even 1-3/8ths. For sure, though, the rat in its all-steel form is a formidable heavy-weight to stuff into such an engine-forward design as the A-body is.
I highly recommend budgeting time and funds to develop the front suspension with the new balance. It is well worth it !!
These are just quick thoughts, based upon what I actually did. I hope some of it helps !
Eric