I get my wire from Marx Parts LL. They carry the 7mm lacquered covered cloth wire found on the 20’s and 30’s engines and they also carry the brass forked fittings,clips and boots,and plug thumbnuts. 7mm cloth covered wire is $1.25/foot here.
Everyone seems to say a manufacturer & not the specs of the wire. Use the electrical values that the ignition requires. I have used neon wire for many magnetos except using hi-flex wire made for flexing & has no steel strands, other applications have the guide strands. Mercury motors have special insulations rating for their hi energy systems. The glass tubes are fragel & require hi flex & quality boots to stop leakage. Good luck with your motor too.