[Cliffradical]

I've done stuff like this, and the experience does have value.
That said, I'd suggest that if you persue this project, just shift your goals and expectations a 'little bit to the left' so to speak.

Buy your Bell, don't do anything to it initially. Run it, plink it, disassemble it and figure it out. Start a swear jar or something for that TM, and just grind the Bell into the ground.
Once you've got your TM (you'll want one eventually), your Bell will be beaten in as well as known to you mechanically. This will give you a good reference point so you can really pick out the differences between the two, and exactly the kind of work you'll need to do to modify or improve the Bell.
It's pretty much the same plan that you have, but extended over a longer period of time.

I have no experience with Bell GBBPs, but if other users are suggesting a KJW over one, I'd jump in with them on that.
KJs are pretty much as 'low end' as I'll go on a GBBP and still expect the thing to work reliably. They're generally regarded as a pretty decent company for sidearms, just with no frills.

My WE M9 as compared to my KJ M9 is a pretty sad little gun. A lot of parts look like they should interchange, but most don't. Some will individually, but put the whole thing together and the slides won't swap.

If people are comparing Bells to WE as equal or lesser, you'd probably end up happier with a KJW.

Edit:
So it's clear that I'm not just hating on WEs, I had a WE 1911 and I actually loved that thing. It was just abundantly clear that it was a dead-end for serious upgrades or mods, so I enjoyed it for what it was. Good enough for use as a typical airsoft sidearm, very loud, fun recoil, worked fine. The mag it came with was flaky, but the extra I bought was a-ok. Lack of cross-compatibility with mags is ultimately what killed it for me, because if I was going to have a beater/ vanity gun I wanted one that could draw from the same resource pool as the eventual hot-shit-fancy-pants one I wanted to build.
Something to consider.