1970 350 questions

[Chris_oz]

Hi all,

I have the factory 350 in my Longhorn, it has 70k on it and runs very well, a small amount of smoke on start if it’s been sitting for a week or so, but otherwise it runs like a new one.
I plan on doing a few things to it to increase its HP without going crazy.

Plans include:

Alloy heads, not sure which, but will have 185cc runner, 2.020/1.60 valves, 64cc chamber, screw in rocker studs. Looking at Pro Maxx or Edelbrock E street.
Edelbrock rpm performer intake.
Comp Cams XE268H-10 cam, with double row timing chain and new lifters.
1-5/8” tri Y headers.
Sniper EFI
I currently have Pertronix ignition and it works well.

I will decide if I am going to freshen up the bottom end when I pull the heads, but given how well it runs, I am hopeful it won’t be required.

I would like to know what sort of pressure I should get from a compression test, it’s a stock engine, 255hp with 9:1 CR
I was thinking 145-150 psi would be pretty close, but would like to hear what others have gotten. I could not see anything in the manual.

If I run 64cc head on the stock bottom end with a .015 gasket, I am hoping the CR will be 10:1 or close, like to keep it under 10.5:1
If anyone knows what the head chamber volume is on stock 1970 heads that would be great, I don’t have a casting number, but can get one if required.

I am happy to listen to recommendations on cams if you know of a better cam that will work with my planned parts.
Truck will be auto, stock converter (for now) and 4.56 rear end on 30" tyres

I would love to build a 383 but wary of doing it on a stock 2 bolt bottom end and a fresh top end on my 350 will do everything I want.

Thanks in advance