Block-to-Radiator Dimension, etc.

[DransportGarage]

I am changing over to a 383 stroker from the ol' 6-cylinder. The cab is off the frame, and I'd like to weld in the crossmembers. I have 3 questions:

1) What dimension should I leave between the radiator and the water pump mounting surface on the block?

2) Right now, the radiator/core support is just bolted to the mounts at the bottom. When the inner fenders are put on, does the radiator get pulled toward the front or the truck, toward the cowl, or neither? I seem to remember doing this when I put the front end together the last time.)

3) I have the engine crossmember angling toward the rear. (See pic #2.) If I angle it toward the front it looks like it will hit the IFS. Is it OK to angle it toward the rear?

Thanks,
Bob