Hi,
Why not just replace the sear? It was probably shortened for the skinny gun. Chambers or TOW should have the part and you should be able to get it already drilled and heat treated. Hopefully, your lock was not a kit someone built because then all bets on easily fitting replacement parts are off. I suspect that if your trigger just hits the sear at its end, you are likely to have a pretty mushy trigger pull unless the sear is fitted very precisely to the lock plate and bridle.
dave