Originally Posted by Stretch

Why was the fluid too high?
During the engine swap the torque converter lost alot of fluid. I refilled to bring it to the mark but the ground may not have been level enough and gave a false reading.

Does your G wagon share a radiator with a transmission oil cooler?
Yes it does

Are you sure the fluid is now correct?
Yes

Have you checked the Bowden cable / accelerator linkage?
Yes those are all in place

Have you checked the gear selector rod and bushings? (Probably not this if the car moves but I like to go down the whole list!)
Good there

Have you checked the working pressure? (you need a gauge for this)
I have not will do that tomorrow

(All simple stuff - I reckon you are better off looking for the simple if you haven't done so already before you start thinking about more complicated stuff)