Thanks to all who answered. The depth of knowledge and experience here never fails to impress.
I think I've made my decision, and I'm going to give it a try. Since it doesn't require any permanent changes to the frame or slide, and I just acquired (a Christmas present - I have a great wife) 9mm Para Pro Custom (and, according to Para, the magazines will work with both cartridges), it now seems like a no-brainer to order a barrel and bushing. Happily, Novak is only about an hours drive from me, and it needs a trigger job, anyway.
It does raise some other questions, however; Which barrel (Bar-Sto, Wilson, et al, and realizing that there will be differing opinions); do I need a different recoil spring and/or buffer, and most of all; is there anything important that I don't know to ask about?
Sorry if these are elementary questions. I'm an experienced shooter and reloader, and own eight 1911's, but the only thing I know about working on Browning's masterpiece is that I need to let a gunsmith do it.
Thanks again
Old Fed