Having done this conversion myself, it is worth fitting a P6 crankshaft pulley and water pump ( and matching front cover ) as the p6 set up is shorter than the sd1 or range rover set up is and will give more space to fit your radiator, also you will need a remote oil filter take off ( use the MGB V8 one )as the standard ones will hit the chassis.
A small tip with the exhaust manifolds MGB V8 tubular block hugger manifolds fit with nearly no problems, also replace the starter motor with a aftermarket reduction gear starter ( SD1 type ) as the range rover one's solenoid hits the steering column and the SD1 starter ( which will just fit ) is not that good and is very hard to change when in the car.