Hi Zinhead:
Here's a great source for starters and alternators, Alfa or otherwise:
http://autoexpress.safeshopper.com/
I've got the later gear-reduction starters on both my Spider's, and sent one to them for a rebuild a few years ago. It came back like new, for ~$100, and it's one of tne nicest rebuilds I've ever seen. 3 year warranty, too.
Just one more thing, I'd avoid the larger 1.1hp starter, unless you've got the proper brace to fasten it to the motor mount on that side. I've seen quite a few 115's, before and after '75, with that starter, and just about as many cracked bellhousings over the years (my '74 Spider included). Use either the correct 0.7hp for your year, or one of the late gear-reduction starters.
Regards,
Dean
Lutz, FL
'74 & '87 Spider Veloce's