You always need to check for interference, but I don't recall much if any issues on Stage II blocks. It has been a while since I dropped a crank in a virgin block though.
If you're running a 3.625" stroke you'll need to clearance the bottom of the cylinders and the top side of the big end of the rods just like you would in a stock block.
Thanks for correcting me Neal. I remembered the rods, but it has been too long since working with a virgin block. I do have an on-center virgin block left though.