First thought is what width of chain you will use, and my first preference for use with Asian freewheels is modern 9-sp chain, crankset allowing.

Of course the bolt length is correctible in all cases with a washer under the bolt head.

Pullies tend to come in two widths, .41" (traditional) and .34" (~9-speed onward). Modern Campag may be somewhat in-between, as they do everything possible to force use of their bits.

I like the idea of choosing a larger guide pulley, so sad that this can't be done on the venerable Allvit, since one of the top pulley's bearing cones has a threaded snout.