This is not a big problem. You will have to deal with the usual suspects:
I don't know if you have front or side motor mounts on the new engine, and I am assuming you also have the bell housing.
You probably have an SM 420 going in, and this could posssibly cause some minor bell housing/clutch and brake pedal alinement/clearances issues, not much to worry about. I suspect figuring out the system to mount the pedal assembly will be your biggest problem. This can be remedied by getting a modified bell housng from Jim Carter or welding a bracket of some kind to your replacement bell housing or ???
The SM 420 is a much bigger transmission than the original. When I swapped mine, I had to get creative with the access hole in the floor, again easy fix using a hack saw and fiberglass.
You will probably need to have a new front drive shaft made. The SM 420 is also longer than the original. I hade the original shortened, it was not too expensive and worked out great.
The SM 420 is a tremendous improvement over the original.
This is not a very difficult swap in the big picture but will require some work and a little creativity.
