Stop in for a cup of coffee

Can those alternators be converted to dual field?

I have a pile of the single field ones that I took off cars that I electronic ignition converted.

I convert them all because I don't fiddle with points

You can run electronic ignition with single field or dual feed alternators...

It's the voltage regulator that determines if you need a single or dual field alternator... Electronic voltage regulator (later style) vs solid state (early style)...