Yes you can fit a 4be1 in instead of a 4bd1. The be1 has 2 different injector pumps, an inline A pump same as a bd1 and a rotary pump, the rotary is not as common here. Manifolds can be different, and the sump is a different depth to the 4b1, found that out the hard way.
There is a build going on here with a 4be1 going into a disco1, might be worth a look.
Stroke and bore are different between a bd1 and be1 too.

