Mill decisions

That's alittle over 700 hp at the crank. I would go with the biggest stroke that will fit and the best rods you can buy like oliver or you could go to Manleys pro I beam which are cheaper(1200 bucks). Also you can go with chevy rod journals and get some Howard billet rods for cheaper yet and the extra clearance will go along way when you have the grinder out clearancing the block. Pistons with probably be custom ones since the stroke is not all that common, Ross or CP can hook you up for around 700 bucks(don't forget the Howard rods are chevy size wrist pins). I wouldn't go W9 because they cost way too much to make them work and good luck finding headers that are under chassis. A nicely ported set of W2's can get you in the 550+range with a small roller cam plus you can still drive it around town. The rest of the power will have to be from N20. For the money I would just build the best bottom end you can, put a small roller cam and port your stock heads and use the N20 for the rest of the power. Either way I'm still not sure if the 4 head bolts per cylinder will take that much power.