Other than what the other poster said
before I clicked, my first thought ran to "bet it's an old Colt SAA!" Nothing beats a 1st Gen Colt--in the gun world--in that "admiring" department! Snick, snick, snick, snick. Looks to be of that limited period (a few yrs early 1900s) of the rounded triggerguard. (Check the ones from the 1800s and later 1900s (1st, 2nd, and 3rd Gens) for comparison. Doesn't necessarily increase, but does not decrease, value--but is kind of a neat distinguishing feature. One of the few outwardly visible changes Colt made over the years that a layperson can spot even from a few feet if looking/comparing carefully.
As someone else already mentioned, careful how you clean, but otherwise don't have to necessarily coddle it like an egg IMO. However, I'd keep firing, if any, to to reduced ("cowboy") loads, no BP. Though I probably wouldn't fire it--there are plenty later ones for that--but wouldn't totally blame someone for wanting to! If in need of actual repair (lock up, etc) get it done by a conscientious/qualified SAA smith and it won't hurt value.
I'd leave the grips alone, including if it has minor blemishes or cracks, and even perhaps consider storing them. If they're falling apart, I'd find another set of period grips just like them--won't hurt value (warn grips are charming; totally broken and dysfunctional ones OTOH add nothing--unless it's a Custer gun! Just think, back then
they would have replaced them!. Genuine original grips are pricey, however. Nothing wrong also with getting some decent replicas for daily handling. A new set (of replicas) can be carefully wooled and/or judiciously sanded down to "antique" them and mimic the old ones. You'd presumably only be fooling yourself and not be trying to pass them off as original to a buyer--and a savvy SAA collector will know anyway--so no matter,...and you're preserving the old ones.
Ditto the above re replacing the mainspring--especially if shooting it, but even if cocking it, dry. firing (pref snap cap'ing) etc--I'd think about it and stowing the original. Can always be reinstalled...but the last thing you want is that breaking on you "for no reason" just 'cause you were playing with it. Other than that, your cleaning and a function (four clicks, etc) and tune check, I'd leave it alone.
If you end up with the gun, have it lettered from Colt, unless it's a "humped up" gun--one with mixed, especially 2nd Gen parts (cylinder, barrel, etc, which many 1st Gens have been so-modified, and in which case not worth the letter...just enjoy. The letter is a couple hundred $ at most depending on "rush" or not. As you say, too bad the specific reason you would get the gun, but hope you do otherwise!
Great gun and round!