And by the way, that is a great price for a running GPW. A guy looking for a GPW engine for his GPW Jeep would probably pay 4 times that amount for it.
The GPW engines and original 3A engines are both basically L-134s. There are some minor differences, but you really have a "bolt and go" situation. The major difference is the front engine plate, but if this GPW engine came out of a 3A, then this issue has already been addressed.
What's the difference between the Gpw and cj3a motor? My friend has a gp3 motor he will sell me for 350 with standard bore. It was in his 52 cj3a. I think it was swapped into it at some point.