Brief comment:
If that's not enough work, get a late Nissan VQ40 V6 motor (.009" larger pitch) and have DOHC and 4 valves, and fabricate a cam drive.
Why do all this work? For 1/4 of the price you can get a ready to run 4200.
After running a well built 292 and the 4200 for me its a no brainer.
No dought that 12 port head makes the 250/292 work after seeing the mighty6 truck in Texas its a work of art. Just pricey. All said and done I bet the 12 port head with headers and intake etc will be >$4000.
Low mileage 4200 about $1000, turbo $700, turbo manifold $900, bigger injectors $300. <<< == 450 to 500 HP for $2900.
