360 Advice Needed - Autocross / Street Engine Build

I'll throw my .02 in on this, as the discussion has evolved.
Its possible to use the cam to get a higher CR engine run on pump gas. But, yea, I think that's something you want to work with a cam guy and engine builder with plenty of experience in doing.

But what I thought might offer is my experience has been similar to a few others - looking at squeezing more Hp is not neccessary. I too will be going to a smaller, more torquey, cam over my current and previous choice.

Also, I've learned that autocross is such a different game than track or 1/4 mile. You want excellent throttle response and torque at very low speeds. Like a road course, torque off the corner is the main goal. One issue on the road course with the torqueflite is that it does eat up some power. I think you'll still have plenty of fun.

My point with all this is look for a good torque curve - and maybe a little lower in the rpm range than you first mentioned. You may not care about vacuum, but it is important to have an engine that can spin up quick. Of course you can run a loose converter, but for doing all the different things mentioned (autocross, street, road course) it may not be the best way. That said, I ran a TurboAction medium stall with 3.23 gears and small tires (24" competion, 25" street) for years. It wasn't bad at all.

As far as exhaust manifolds go, that's a toughie. Its not just about flow, there's also reversion at lower rpm - and that's worse with a high overlap cam. There's a couple of CompCams that may be of interest. 20-309-4 The other IIRC was the XE268. However, there's no point in trading ramp rate for reliability. My old 340 had the HE 280 cam in it and I think the XE 268 might be a bit better in torque in the low to mid (3000) rpm range. 340 exhaust manifolds is what I was using until a couple of years ago. Car ran best of 13.77 99.5mph