Ok...here is my question..

Big cam..big carb....inadequate heads.

The 143 are marginally below decent. They are small valve press in studs. You have a big cam in the block. You need 2.11/1.77 valves.

You also have an OD trans with 3.73 gears.

You do have access to 143 heads..but why use them? You asked how to rectify a botched build and using 143 heads IMO, is a band aid.

Could they work? Yes. But considering everything else in your build, the heads will still your weak point. If you are trying to rectify someone else's botched build and may have to rebuild heads...consider getting large valve, screw in stud 72 cc heads.

I only say this because I have made the same mistakes when I was 17...low on money, and quick to fix. I built a 400 with a lunati 245 single profile cam with 110. 850 caddy q jet, headers..3.55 gear..and 5C heads. Dismal 8.1 compression. Switched to #46 press in small valve heads. Spring seat pressure too much for the studs.

But wtf do I know...