Mac bars
1 of my 250 s has been changed to a rim drive,I don't know the Oregon number.I don't know if Baileys or one of As suppliers carry these or not,it my take an e-mail,or phone call.If not,MSC,carrys the spur sprockets.As far as the bars,it would take a large mount McCulloch [3/8" studs],I don't think anybody makes them anymore.You could use The one you have[I assume it is a hardnose],most likely .063 slot,but could be .058.I have used Stihl mount bars,and used bushings to take up the slack from the studs to the 12 or so mm slot in the bar.This calls for modifying the oil hole and bar adjusting hole.I 've been able to find a few,on e-bay.A few of the a-site members,have lots of them.I try and stay with the bar style.of the time period,because of the fact I restore them.Case in point is the bar in the picture,which is an Oregon"armor tip"and it still had the decals on it ,when I got it,but this is just a personal preference.In one of Weimedog's posts,he tells of a saw shop in Ny,that has oodles of nos parts for these saws,check it out.Good luck