One advantage to over-boring the MC is you'll push more fluid & have more oomph to the brakes. As long as the new seals fit properly and dont flip over anyway.
I would look around and try to find any local small machine shops or hobby machinists, could get it sleeved with stainless at a reasonable price.
Another option is to look for other MC's form later years that would bolt on or adapt easily.
As for that whole safety issue, singe circut brakes are a real risk if you half-arse anything. One part poos, the whole system poos.
The idea of some cell-tard pulling out in front of me (happens a lot, even in my monster of a bolt) stomping the brakes, and having my foot hit the deck with no resistance is NOT on my list of favorite activities. Been there, pucker factor 12 engaged and it took me an hour to pull my shorts back out. Thank God for functional shaft brakes!
