I think we drove through Bozeman one year - I seem to remember a really big Rancher's breakfast.
Anyway, here's the full lineup of Strombecker "Hemi" type motors. Red is the high-performance aftermarket one (though included in a few later kits); the blue endbell is the standard motor for their kit cars; the green one you know about... and I have no idea where the one with the black or dark blue endbell comes in! It's the same size as the greenie, and they're shorter than the others, but otherwise more like the bigger ones...
Anyway, I have an extra green motor if you can't find one in the States - I'm in France so it won't be instant gratification either!
Don