Thought I would update the progress.
After making the rear frame I needed to finalize the engine location so I made the conversion plate.
I opted to use a Subaru 5 speed transaxle modified to drive out of the front diff only.
I measured the dowls on the Subaru box and Nissan engine.
Machining a 32mm hole in the centre allows me to put a spigot bearing in then after drilling the dowls I can drop the box on and check it fits.
The rest of the plate holes are transfer punched, scribe and cut on the band saw, then linished.
The inner hole I used a pattern fixed to the plate then ran around the inside with a router.
When The engine comes out the plate will be heavily drilled out to reduce the weight