I've adapted Stihl bars to fit old McCullochs and Homelites by just turning on the lathe what really are just thick washers .It's much easier to say find a 36" Stihl mount bar than to find the same in either Homelite or McCulloch ,large mount .
Another little tip on certain models like the Partner P100 OEM bars are next to impossible to find .If you use Husqvarna 2100 bar plates a Husqvarna bar will fit ,no alteration needed .If you can even find McCulloch SP 1000 plates ,10 series McCulloch bars will work.Again a Husqvarna 36" is a lot easier to find than a 10 series Mac 36" .