Sounds good!
I just got in a .460 Rowland kit from Authentic .460 Rowland people. I'm converting one of my Glock 21s.
I have a Clark kit in a Kimber 1911, and have some loads made up for that, so I measured throats. The Glock barrel's throat is .039" longer than the Clark which means there shouldn't be an issue, if anything the Glock could be slightly slower, all else being equal. The Rowland loads I like are only in the 25-26 Kpsi range anyway.
Back to your 1911. It should run pretty good with the setup you describe, and the cartridge is a hoot. You are right about the brass, I ended up buying a stash of +P because, again, the loads I like are not that far above +P pressure. If your barrel has good support, you may consider that unless you're running balls-to-the-walls.
