One thing that may be worth your time if you do a good number of sets with bad rubber wire is to find an ample source of cloth wire: a tube based organ.
A few years back I bought a Baldwin organ to scrap at a thrift shop for $10. It contained dozens of 6SN7s (I could get north of $100 for those alone), some 12AU7s and AX7s, and a awesome stereo amp chassis which I was able to get ~$250 out of (part of me wishes I'd kept it)....Among all the great parts the thing had, was the ~5' cloth harnesses connecting the keyboards and pedals to the tone chassis. Those harnesses have me set for fresh, good quality cloth wiring for the foreseeable future.