Isn't that kind of high compression for a turbo motor on the street? Definitely build a high quench motor from a 400 block or aftermarket as mentioned above with aluminum heads with studs top and bottom.

Have you considered running a Sniper or a pro-flo 4 multi point EFI?

1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)