Oh, ha! I expected to get harassed about a dinky little alternator The large case should be a perfect drop in, as I've read about many easy installs.
That same reading lead me to believe the small case would work just fine too, BUT it appears that a slight changeup in the belts or a specialty bolt is required.
U could...in theory...take a carrige bolt of correct size thread...ground the square down roundish...till fits in...slot the bolts head w thin cutoff wheelhead and bobs yer uncle...
Just be creative