What is your electronics work like MJ?
I've seen an X Box stripped down and fitted in component parts spread around the car. The disc tray ejected from the air vent. It wasn't fitted in a beat but the principle is the same.
Engine replacement? Well I was defeted by the 700cc conversion which seemed like the most simple option. It wasn't a straight forward boreout and fit oversized pistons and whilst I don't doubt it's possible at £200 per mistake I gave up having damaged 2 pistons. I think the only other engine that will fit in the space will be one from a VFR but how you would tie that to a gearbox would be the problem to solve.
If it ain't broke, take it apart and see how it works