Urk.
Best rule for unfamiliar gun goodies- ASK FIRST, order later.
You can't really silver solder a front sight assy with the tritium lamp already installed in it, because of the heat. And I personally wouldn't trust epoxy to hold well enough for such a critical component. Of course, other members' mileage may vary on that one. Just to note, I had a set put on one of my 870s when Scattergun was still in business, before they sold out to Wilson, and they pinned it as well as epoxying it. Louis Awerbuck said even that wasn't enough to hold it reliably, and he sees more 'working' shotguns in a month than I have all my life. I tend to listen to Louis, OMMMV there too. Just so you know, if you ever take his shotgun class, one of the first things he will do on the line is try to physically push the sights off of every shotgun with sights on the range. BTDT... my front sight was silver soldered on and stayed put when Louis leaned on it.
They used to make a jig for locating the holes and drilling the receiver for the ST/Wilson rear sight, don't know if they still do or not. That might be a help, if you need it.
FWIW,
lpl