I agree with Scott about finding a 340 block/engine if you can and store it until such time as you decide you want it. As for your current plan, I would go with a 360 based 408 and I would use the K-1 technologies rotating assembly, a pain to get but the quality is second to none from what I can see. And yea, if I need a small block this is the route I would go, why give up the cubes and the power.