I'm not into the lil engines, but I think I would be finding a way to adjust the timing before I went to all the expense of hotrodding it!!!

Maybe an MSD solution?

If the engine is setup correctly you shouldn't have to take the timing out anyway. I run 38 total on my V8s, and if they ping, it is a problem that needs to be addressed, not detuned.

I just got done reading an article on the AMC Forum where they fully modded a small AM V8 (304 w/390 crank) for a crap-gas only dyno shootout. They were over 11.5~1 and made over 600HP!!!

Nobody said you had to keep the 4.0, either. The old Rambler 199 is WAY stronger & capable of outstanding HP & TQ numbers with a good rebuild & a boneyard turbo. The 199 AM 6 popper modified for Indy with a turbo made 640HP. With factory crank & rods, I believe.