I tested out a few things, including some aftermarket parts.
First of all, I didn't find any spacers. I'm not sure what these look like, but perhaps the NASCAR version doesn't have them? This version also does not have lights - maybe they are something related to that? There is a tall structure at the front, is that the front one? I don't see anything at the back that can be taken out, and there is nothing between the body posts and the chassis.
Second, the Typhoon motors fit well. The long shaft that hangs out the other side can be used for the pinion on this one (it is if anything too long, and may need to be cut slightly) and the endbell fits fine into the mount if you remove the Pioneer pinion. I have a QS that had a jammed pinion (which meant that the shaft had to be cut off on the end bell side) so I will now be able to use that in this car. This should give it better braking.
Third, the standard Slot.It bushings seem to fit this car. The axle will need to be quite short, maybe 44mm or so.
Fourth, the CB Design 15x7 'steel' wheels are perfect underneath it and the Paul Gage tyres (Ninco fitment, also sold to fit standard Monogram NASCAR wheels) seem to clear everything.
Fifth, the Sloting Plus standard screw fit guide works well with the B-NOVA GM-2 conversion and should all go together well.
I've only test-fitted stuff at this stage but with these few mods and the standard wiring loom replaced with simple wires and some lead in there this looks like it could be a great car.
Here are some photos.
Showing the length of the Pioneer shaft relative to the crown gear:

CB Design (Slot Car Corner) wheels and Paul Gage tyres clear everything okay:


Test fit of B-NOVA GM-2 kit and Sloting Plus guide:

