The "need" for a set trigger, in many cases, is a product of our 21st C society. Many people are not willing to put in the time and effort to make a simple trigger work for them. I have a client who shoots a 20 gauge smoothbore competitively, and he has had me work on his locks (he has several for the same gun, in case one fails at a match) so that the trigger pull is a crisp 2# or less. Most of us here will agree that this is ridiculously light for a trade gun lock, yet my friend insists upon it. Each to his own...
Having thrown him under the bus, I put a single set trigger in my Mark Silver Chambers' Virginia rifle. I bought the trigger from MBS, and it fit easily into that rifle without any issues. I shoot that rifle really well, and consider it my best and favourite offhand rifle, in .50 cal. and at 10 pounds. I bought a second barrel for the rifle a few years ago, a .60 cal barrel from Barbie Chambers, and that lightened up the rifle considerably...a wonderful shooter!