Came across this facebook thread about sleeving a 360 which also required machining of the cases. What caught my attention was in the comments below:

Just throwing this out there again (even though this looks like a really cool option!) that Athens Sportscycle in Athens Ohio has brand new Wiseco pistons that they had made for the 360’s in 80.50mm and 81.00mm . 740-592-1692 and ask for Ryan Moore.

Below is the original facebook thread. Hope this is true and helps out anyone who needs an oversize 360 piston.

1972 Yamaha DT2-MX 250 RT2-MX 360 AT2-M 125 | Thought I would share this, customer asked us to make a fit a new sleeve to his 360 cylinder but to use a 85mm DT400 piston | Facebook