My friend who makes the tang sights, and also a windage adj. front sight base (std 3/8" or your special need, which will then take your front sight), very traditional 'lollipop' peep sights, and custom size OD or peep aperture eyecups has OKed posting his contact info:
Terry Morgan
20619 Blank Pike Rd.
Wapakoneta, Ohio 45895-8071
419-568-2711 (days, he's a retired gentleman and does this to keep 'involved in the shooting sports'. Just tell him that guy in Wisconsin sent you, he'll know)
BTW, Ive also got the wrist/staff angle info that the new Marbles uses for their H&R BC and NEF Survivor models. I'll dig it out and post it or have Tim put it in the FAQs.
When you mount any tang sight base up on the wrist you should scrape a placement on the wood that matches the base (+1 that use of tape getting things lined up initially). I like to use the rifle's open sights which are already sighted it to look at through the peep while lining it up, the drill and mount. You can also do this with the BC rear peep still mounted to get the tang sight right. If you have the tang sight truely verticle the windage wont change as you make elevation adjustments. Drilling, of course, means using a drill press, if you dont have a mill, NOT freehand unless you are very skilled and know it (that is, if you have any doubts, use a drill press and properly jig up and eyeball before you turn it on).
Yeah, I know it sounds futzty, but you will dazzle and amaze your friends.........