Lose the Japanese engine and get the original Morris engine and transmission back, and learn the joys of SU side draught carburetors! A bit of tuning and some minor work, and the Morris 1500 is a great, durable engine. The wood looks pretty good on this one. Not so sure about the yellow, but if it is original, I would keep it. All in all, a cute little runabout.
The injected O-series 2 liter is even more fun. You only have to just turn it sideways: http://www.aronline.co.uk/blogs/cars/austin/maestromontego/unsung-heroes-mg-maestro-2-0-efi/