drbotts - yeah, I suspected the concern was will trapped gas but you got better reasoning than I did. At least in my case, I'm working with a new regulator.
Folks on this forum convert and rebuild regs all the time so if there was even one insident it would result in a major discussion.
I havn't had time to mess around with my reg yet nor chase down the 320 fitting. I noticed makinwar has or had 350 nipple/nut so I'm thinking of just going that route.
Thanks for the additional info!