By changing the factory sear to a Volquartsen sear makes a world of difference. It will lighten the trigger pull quite a bit, usually 2-2 1/2 lbs. The Volquartsen trigger will allow you to take up the pre-travel and over-travel easily without having to disassemble the pistol, once it is installed.
I put a Volquartsen trigger, hammer, sear and spring kit in my MKII a few years ago, after wearing out the factory sear. I will never own another one without it. It is like a whole new gun, it is just so much easier to shoot well with a good trigger. It is well worth it IMHO.
In the words of someone on another forum, "Holy Jesus Christ monkey balls fantastic!"
I just got the sear and it feels fantastic. I don't know how it is with the hammer also, but I imagine it's probably not worth the $40 or so it costs. I don't think the amount better it could possibly get would justify the cost.
I would get one. They do make a difference. That is what's so good about the MKII, there are lots of after market parts that make an improvement. I got one from Volquartsen once that made the trigger pull around #1. That was way too light. I sent it back for an exchange with no problem. The customer service at Volquartsen is something you can't find much anymore. Great company and great employees. I also have the Volquartsen hammer which is a great match to the sear. Well worth it for bullseye shooting.
The Ruger sear and hammer can be worked by a competent smith to where the performance is as good as the VQ, with the exception that the VQ trigger has a pretravel adjust which the stock trigger does not (the stock trigger does have an overtravel adjust only).
As for drop in with no rework, the VQ parts do improve performance.