Sorry Rick
I expect everyone is waiting for me to answer this one!
Wheels on the P6 are a bit of a black art, thanks to the constriction of the rear wheel arch at the bottom front of the "mudguard" formed by the side of the boot and the D post area of the base unit.
The only wheel that is a sure fire winner is the SD1 Vitesse 15" alloy, and then if you want to use the widest possible tyre (which is 205) you need to machine about 3.5mm off the back. Otherwise you are almost certainly into taking a lump hammer to the D post area, losing the D post complete with weatherseal to the back door, running underdiameter tyres or a combination of all. It all depends how serious you want to be. You are right about the Jeep wheels though, and there have been photos around of several cars fitted, albeit with some or all of the compromises above.
Another wheel I have become aware of recently, but don't know much about is the wheel fitted to some Reliant Scimitars. It appears visually identical to the composite wheel (aluminium centre and chrome steel rim) fitted to MGB V8's, but with the Rover 5 stud centre to suit the Scimitar. I've no information what the rim width or offset is though. Because it is a composite wheel it ought to be reasonably simple to get an alternative rim fitted to achieve the required width and offset.
Use the search function to access a huge amount of information stored on here, or if you get stuck pm me and I'll do what I can to help.
Best Regards
Chris