Having built Many of these, my .02 is not to Over-think these things. for a high torque 550-670'is horse motor theyt can't be beat. Find a good solid block like this one 71 230 but not a cold weather uber-thick main and drop in a 4.15 to 4.30" crankwith a decent st of 280-320 CFM heads with a streetable 250-265 ish @.050 cam and let it go; there's really not much point making more top end power if you can't make the torque you already have hook up. The best, most reliable motors are the ones that keep the torque peak in the 3800-4400 RPM range, when you really turn up the wick with big 360-380 cfm Max Wedge heads they can make 675-725+ HP but it requires a lot more spring/cooling/converter and tire to really make it pay off and 90% of people won't even know the difference between a 620HP and 720HP motor below ~5000 RPM anyway. Torque is what sets you back in the seat and as strong as B/RB blocks are they are (after all) 2 bolt main motors designed for modest RPM torque peaks... If you think about it....there's a reason Hemi's had/have cross bolted Mains....durability.

I'm not saying you can't build a reliable 700 hp motor and drive it on the street, it';s just that it generally costs a lot more to achieve a powerband improvement that is usually only appreciated above an RPM you (for most people) seldom get to use outside of a drag strip.

Again, don't over-think things, build it the way you want it, this is the Race forum so (although well-intentioned) a lot of what you'll hear on this forum will lean toward "super-sizing" the build. You can, but don't feel you need to. MHO only