A few years ago I bought a K1 motor from a guy which had a nicely ported head, a nice strong Ivan Tighe cam and a big bore kit.
This motor had been sitting around for many years uncovered in his shed.
The wasps had made their home inside the head and it was full of nests.
I pulled this motor down and found that the pistons had been attacked with a die grinder presumabley to lighten them up a bit.
The pistons are Honda CB360 (67mm) with 16mm pins and the stock rods that came out of this motor had the small ends bored to suit.
At least it did hold together.