Frankenstein's KZ550

Hello all,
I am new to the forum and have just purchased a project bike that is a bit if a Frankenstein's Monster. It is registered as a 1983 KZ550 but here is what it actually is:
I think it is a 1981 KZ550C LTD engine, tank , fork, seat and side panels, mounted on a 1983 KZ750 Frame (adjustments have been made). It has chromed spoked wheels, after market generic meters, possibly the original head light, and a 4 into 1 exhaust from a Triumph bike (also some adjustments have been made). So I'm not sure how I'm going to be received in this forum because there is really no way I can afford to put this back to original, but I do hope to make it run well and enjoy it.

My first question is I am having problems being sure what model engine to buy parts for. The bike has mismatched frame and engine serials and owing to having been parked un-registered for more than a year it has been given an new VIN number by New Zealand Transit where I live. The engine serial number is KZ550AE019311. Based on some research it think this is a 1981 KZ550-C2 engine off an LTD. Can anyone verify that for me? Thanks

WELCOME