I hear ya on the small town reality. I've tested more than a few 383's and every time they have any kind of AFR head they go well over 500 HP. Love Scorpion rockers for value. Youre results from carb to EFI mimic my own. Check the averages--carb was WAY better in my case even thought the peaks were very close with EFI.
I would love to see an AFR SBM head someday but I doubt it will happen. If I had some serious funds I would handle the pattern making and cover the cost of a run at a foundry and then handle the final machining--but alas this is one of my better dreams. J.Rob