2 bolt blocks are good for 450-500hp. What are you planning on getting from this motor? Also, a machine shop can make your 2 bolt block a 4 bolt splayed main which is waaaay stronger than the stock 4 bolt block. All you need is conversion caps, ARP studs, and some machine work. I did one many moons ago and it was $400 or less, probably $500 these days.