Whatever your previous owner used it will break down with heat. Read the manufacturers blurb on Loctite, Araldite and so on to confirm this.
You don't want to go berserk with excessive heat, no direct flame or oxy torch or such like. I suggest you get to work with a paint stripping heat gun and slowly and evenly heat the cylinders through out, keep it hot as you can for for a while, and then try again. Patience is all.
RogerWilko is probably spot on with the reason why this happened. As an Australian he will also tell you if you're desperate you can have these ruts filled with bronze, the bores cleaned up and continue riding. Because of the superb spare parts supply and after sales service provided by British motorcycle makers (not) Australians learnt to do all sorts of things to keep their bikes on the road.
The serious wear surfaces in a cylinder are fore and aft, the sides containing your ruts do not share the same wear pattern so the bronze is quite adequate.
You will probably find all the parts you need but keep the above in mind if all else fails.
Cheers,