[Classicrocjunkie]

is the shaking coming through the steering wheel? Would assume so and if its only occuring through the drive train while accelerating i have a couple ideas.

Trans mount is not likely. Try your other ones, but i don't think they are going to be the cause. If it was an out of balance wheel it would continue to shake even after you let off the gas. Are you lowered? If so on what?

Did you ever invest in hub centric rings for your rims? Is so, might want to check and make sure they are still on there from when you got your car back from the shop who did the motor swap. That would cause that issue. If your lowered on stock struts and lowering springs, your drive shafts are prolly kissed good bye. Been there done that once myself.

Those are just a few, ok back to my all nighter studying deal.