Single field Alternator rebuild

Hi guys.. so I popped into the starter/alt rebuild shop and it just happens the preferred alternator rebuild guy is on holidays..
To get me up and going.. is there a suggested updated square back alternator I can purchase from my local parts store ?
I did a fast research and looks like the lowest AMP rating available is 55..
I realize I'll have to ground the 2nd field to case ..
Anything else I should look for?
Thanks.