I have a couple of 77's. Ones a "tang safety" and the other is the 3 position wing on the shroud and two SS Alaskans in 375 Ruger.
Triggers were not bad, but not that good either. All I did was carefully polish the sear faces with a fine diamond dust impregnated hard rubber "stone", being careful to NOT change the angles of the faces. Then pulled the trigger return springs and carefully nipped off a quarter of a coil at a time, reinstalled them until I got the pull weights down to just under 3#. Have to be VERY careful you don't take too much coil off or the trigger won't return/reset if you do.
And, if you do screw up the return spring, you can match up more than adequate replacements at a hardware store. I messed up the first one I did and replaced it with a stainless steel one from Ace HDW for about a buck. Once I was sure it worked fine, ended up converting the others to the same SS return spring.
Edited to add: I've done this on 5-6 other friends Rugers, all of my M98 variants, and a couple of Win 70's. Not rocket science, just be careful and go slow. It's a lot easier to take metal off than to put it back.