jamesinc;c-147265 wroteAlso wondering what the correct order of operations should be. I would think, because there's risk of damaging the valve seats, the best thing would be to port the head first, then have it machined for the larger valves.
My machinist cuts the seats and throats the port at the same time.
I can't see an immediate gain from touching the short side radius, but a flow bench would be the only real way to say, yes to leaving the split around the guide on the 531, fuel flow is as important as air.