I'm a skeptical person by nature and have kicked many a "salesman" off my property. This used to horrify my wife and kids but I have taught them over the years that nothing is free and you have to ask yourself "What are they getting out of this?" Sorry a little off topic but I feel this sentiment is shared by IQ and myself.
I don't see the high side of 600HP happening with EQ's and a "portjob". We all know that achieving 80-85% of total potential is relatively easy. So lets say 500-525hp 408 with EQ's is easy that would represent 80-85% POT. Now ramp that up to 90% and you are sitting @ 550 hp IMO. Ramp again to 95% and youre tickling 600hp. Ask any serious race engine builder what it takes going after that last 5%----MEGA time/money and the real kick in the balls is that you may never get there. In fact IME going after that last 5% you often go backwards and make LESS power only to learn a bunch and get tired of that kicked in the balls feeling.
Having said that---I am as curious as a cat and would love to see you try. I'm about to embark on a personal challenge of building a 600HP NA 318. I view my goal easier to attain than yours-and that's a major hint right there. 4" stroke is not the way IMO. J.Rob