I had used Ed Larralde in several instances many years ago. Still have a barreled A1 Mid Range Ballard he installed a barrel for me. I was informed at the time he was selling Saeco molds and had been "familiar" with Mr Barry Darr. Late 70's to early 80's if I remember correctly. He put some 38-55's, 32-40's, and 40-70's and at least 2  45-70's for me. There was a barrel maker in Montana that he used alot in the late 70's. Nice gentleman.

problem with tang sights on Ruger SS rifles is the safety button.  A lot of target-only #1/3 rifles have had the safety mechanism removed, just to simplify things.  I guess they feel that since it is a target range-only rifle a positive safety is not required.  (I have reservations about that myself) 
Some also use the ex-safety slot to anchor a breech seater but a highwall-style breech seater works pretty well.  Steve Durren makes a real nice one, as do the other usual suspects

If there is no safety its a matter of getting the angles of the base correct and then drilling and tapping.  Some have fabricated a new safety button with "wings". That way the bottom of the sight base can be relieved so it bridges over the safety.  the "wings" extend on each side of the base so you can still have an operational safety.  I have a #3 project slowly percolating and I'll go that route myself.

Ooooh! Photos when you've got 'em, please!