My 514 makes 900 hp with EZ heads and a cast 4bbl intake. My engine is 4.440 x 4.150 and peak power is around 7000 RPM.

Your heads are bigger and better than mine so you should make more power. I think either 4.150 or 4.250 stroke will work for you. You'll need a big cam to put the peak power at 7500 rpm. My cam is 282/288 so you'll need to bigger than that.

Dwayne can get you all sorted out in terms of cam, lifters and springs. I don't think you need a tunnel ram to make 900 hp. It is a lot more money and more of a tuning hassle. If it was me I'd spend the money on EFI rather than a tunnel ram and two Dominators. The EFI setup will give you data acquisition as well as precise tuning.

https://www.youtube.com/watch?v=LZcFl7fy6FI