I don't know anything about the old companies you're referring, and I'm not an expert (by any means) slipjoint maker. Frankly I'm a beginner at them, although I've been making knives for a number of years now.
When you say you're applying Nickel silver bolsters to brass *and* 416 liners, I'm confused. Is one liner brass and one 416, are they sandwiched 416 and brass, or are you talking about different knives?
Anyway, the method I've employed for damascus, and dissimilar metal types is hard silver solder (1200 deg high silver content silver brazing, etc) using silver ribbon solder.
steel bolsters to steel liners (stainless or otherwise) can be spot welded, but with damascus the spots will show unless you do some thermal cycling.
If you're peening your pivots, that's one axis of mechanical fastener, so a non-secured blind pin to keep the bolster from spinning should work in conjunction if you do want to braze, but I'd feel more secure with brazing it. For brass liners and nickel silver, a brazing rod that matches the brass or nickel silver may be more appropriate, hopefully another more experienced slipjoint maker can chime in.
If however you're trying to duplicate a specific method/style, it may be a whole different deal entirely.
Not sure if that helps.
