It's like cars I suppose. A V8 HZ ute worth more than a V8 VS ute.
I tell you one thing, the XR 500 motor feels twice as heavy as the CRF450 I had. The crf piston is bigger than the xr one too. The old xr is a real thumper with a long stroke though.
So far it looks like the previous butcher owners undid every bolt with an imperial set of tools. I had to wedge a 3/8 socket on the 10mm cam bolts to undo them. At least they undid.
Tip for any beginner restorers out there,buy good quality tools in both metric and A/F. Don't be tempted to use metric on A/F and vice/versa. Don't use open ended spanners if you can avoid it either. I know you have to sometimes. Never use a shifter/lathe in the hand either!