I've had pretty good luck w/K frame hammers and triggers being operational as drop-ins, but I'm gathering from my readings here that it's kind of a carpshoot. I think my course of action would be to buy an appropriately-aged hammer and give it a try. Use the double-action sear from your present hammer (be careful - there's a little bitty spring under it), and I think confidence will be high for acceptable function. If not, then a 'smith's consult would be indicated. Please do keep us updated.

Good luck,
Larry