Cylinder throat is ideally the same size as LEAD bullet MK.
The idea of a .431" throat when shooting .431" lead bullets (obviously) is- you're not swagging bullets down as they pass through throats, that then have to "bump up"/obturate to seal the bore.
Lead bullets which are undersize for bore (due to the throats swaging them), will experience "blow by"/gas cutting- on the base of bullet when entering the barrel.
This contributes to crap accuracy and usually moderate to severe leading.

First, if you're set on a custom reamer- contact Dave Manson direct and run it by him.
He's a shooter and is always willing to work with you. I have no idea what the upcharge for a custom reamer might be.
You will want the "pilot pack" with the reamer.
The existing throats/chambers on your gun will likely NOT be same sized.
The pilots allow a fit for each chamber/throat, for optimal precision on the cut.
If you use a pilot that is undersize for the throat/cylinder- you will have the cutter want to wobble and not cut "square and plumb". Your accuracy will not be as good as with the correct size pilot.

I have shot 240 gr. XTP's through my MG's (3) that I reamed throats with Manson's .431" reamer.
They shot much better than the stock throats (1.25" to <2" @ 25 yds.) with less pressure.

That said, I might use the XTP's for Whitetail, but not for hogs.
I used 300 gr. XTP's on a 450# hog once and they did not expand, but acted like FMJ bullets. This caused a minor problem, in that- the hog didn't stop (he was headed my direction) and I shot the gun dry with him finally dead, at spitting distance with a head shot.
FWIW, these were fired from a custom Bisley and chrono'd 1275 FPS- well within the velocity design window for expansion.
Hornady makes two different 300 gr. bullets for .45 Colt; one with expansion between 900 and 1300 FPS- for +P Colt and one for .454 Cassull velocities.
I had the correct bullet.
This may well have been a fluke, an isolated incident- but "once burned, twice learned".

Gold Dots didn't exist when I started on my "hunting handgun" journey.
I would most definitely try them today however. They have shot lights out in several AR's, P-35's and 1911's.
I would see what is available in a .44 component bullet from Speer if you plan on using a jacketed bullet.
My hunch is; the Gold Dot bullet might be a better performer on game than the XTP.

I've set up all of my MG's; .41, .44 and ,45 Colt to shoot cast lead.
I favor a gas check bullet as I get ZERO leading with them.
A gas check Keith type, or WFNGC, that is long for caliber has been satisfactorily accurate- and shoots through a large hog- leaving a good blood trail if the game isn't immediately anchored.

Your shooting/hunting scenarios will dictate what bullet you use.
Don't underestimate a good, cast lead bullet for hunting however.

Montana Bullet Works produces a great 255 gr., true Keith type SWC with a gas check. These shoot really well in all my .44 mag guns.
https://www.montanabulletworks.com/p...thentic-keith/

Beartooth Bullets also produces superior cast bullets. You can spec bullet diameter with them as well.
http://beartoothbullets.com/bulletselect/index.htm

I'm with you on the 29-2, I would not screw with it.
It probably deserves to be treasured, or at least treated special.

Regarding the shims you mentioned-
The only way shims will positively impact the double action trigger pull is if the hammer, or trigger are excessively loose in the frame.
The shims go over the pins/studs which hold the trigger/hammer and are secured to the inside of frame.
These shims will tighten the trigger/hammer in the frame so you have some chance of trigger and hammer being square and plumb to each other when firing.
I have experienced maybe two S&W's (of varying timeframe/age) in maybe 30 trigger jobs- where the shims were needed, BEFORE the stoning of the hammer/trigger was begun.
One was a fairly recent manufacture 4" 629-?. It was a MIM/lock gun.

Best of luck on your journey. You'll learn a great deal.
On the back end- when you have it ALL sorted out and the gun shooting to your expectations, game has been taken, it will have been well worth the effort.