It's my understanding that the reason you would pin the ring, is to prevent the potential for the ring gap to be exposed to a port. If that were to occur, cases of "snagged" rings would be commonplace (with disastrous results/destroyed engines). I can't say I've ever seen a 2 stroke piston where the ring was free to turn/"seat" itself. 4 strokes a different story.
Regarding transfer ports, commonly, the design of the crankcase includes areas machined to enhance air flow to the transfer ports (front, rear, and the side opposite the exhaust port). Because generally there are no transfer ports on the exhaust side, there's no need for this machine work on the exhaust port side of the crankcase. So, if we turn the cylinder 90 degrees, even if everything else works out, your 3rd set of transfer ports have been blocked. In this case, the ones that were originally in the front of the cylinder.
These are both of the commonly found issues when considering turning the cylinder. Not having seen this one, not saying either is the case here, only that I'd be pleasantly surprised if that were not the case here..... -Al