Theres several threads on adapting disc's to these old straight axle Stovebolts and those useing stock 16" wheels seems to encounter the same clearance issues.
Course alot depends on the kit and or assembled disc parts you use.
I haven't gone there yet but I try to keep an eye on disc conversion threads as I will eventually go that route also.
Some kits claim that all you need is to buy their optional spacer which kicks the OEM wheel out just enough to clear the caliper.
Other restorers here just simply grind off "just" enough edge material on the calipers to gain the clearance. In looking at some of the pics this isn't a bad mod to do as it's so little theres no compromise in the caliper's integraty.
One or more should chime in with better answers. Unless your 3100 is a daily driver you should be able to work through any clearance issues w/time and patience.
Good luck
Dave
