Thanks for all the replies guys .

I guess the sweet recipe is theres no replacement for displacement
The more you spend on heads the more power
The story never changed.

Yep , theres a few that squeaked close to 500 with a stock crank.
But no telling what compression was or how radical the cam was.

So i guess the moral of the story is -
If you wanna run on pump gas
Design a high quench 9:1 design
Big cubes and just suck up the costs ..

To be continued ..