The mounts for the gbx are handed so can't get them on wrong side, heights would all be wrong, thanks for the suggestion.
I've had a good look back through photos of when I took it all to bits and reckon the engine mounts are too far forward. as Snagger says. Backed this up with a test fit of the bulkhead and the bell housing to gearbox flange was too far forward relative to the bulkhead.
Going to re-drill the holes in the engine mount brackets as far back as I can allowing room to fit the nut underneath. I will still need to slot the transfer box mounts forward by 10mm but reckon