Originally Posted by TheEngineer

With both the 3.875" and 4.00" stroke cranks you'll need to clearance the block. Additionally, you'll need a .900" small base-circle cam and have to check the clearance with the rods and cam lobes.

Both cranks are built to work with the 400 main bearing diameters.

Also, the GM 400 blocks will not hold-up as-well-as Dart 400 blocks.

WD