Browneagle

I hope someone can help me. I am new to this forum so here goes. I just bought a trike that has a Nissan motor for the powerplant. The block is stamped Japan Nissan. I can't seem to identify it though. It is a 4 cylinder motor, twin carbs. The only numbers I have found are:

(1) On the drivers side of the block just above the oilpan the number - 2 782 38806034 :
(2) the other is between what I think is the #1 & #2 cylinder, it is - 66264.

I hope someone can help me out. I would like to rebuild it and put an automatic tranny with it.

Thanks