I dont, I'm collecting it today so will do a bit of investigation over the next few days and see if I can identify it
The engine is definitely a 500, its stamped 498cc. As for the tank and frame I'll have a better look for the frame number and see if I can find itThe tank and frame look more like a CX650C, but that engine is a 500 by the ribbing at the bottom of the block.
The bike was imported, I just dont know where from and was first registered here in 1983It looks like engines with numbers that start with PC02E-40 were used in the CX500E Sports model (AKA Eurosport) in the 1982 model year.
The carbs look like the closer spaced ones used on the CX500E and GL500 but what I can see of your frame looks like it is from one of the other CX500 models. The tank looks like it may be from a CX500C (Custom) so I suspect the frame may be too. 40 years is a long time and engine swaps aren't uncommon...
I think the VIN plate on UK bikes might be behind the right side cover.