I've been working on a project to re-cap several 30+ year old Bryston 2Bs and 2BLPs. As has already been noted, there are a variety of original filter cap values, but I've been using 6800/50 Nichicons with a 105º C rating, and they seem to work fine, although the real test will be how they work in another 30 years.
These amps had been on 24/7 for almost 30 years, and the other thing I found was that the 2.7 KΩ resistor in series with the power/clip LED was well baked, and had damaged the PC board, as well as lifting the traces slightly. I replaced them with another 1/2W, but tried to get the component off the board instead of sitting right on it.
The schematic above seems to be from the original 2B, the one with a green power LED in the middle of the front panel, and two red clip LEDs on either side. A slightly later version, with the bi-colour LEDs is also on their web site. Interestingly, both drawings have a small error. There is no connection shown between the output transistors' collectors and the speaker output. There should be a connection dot just to the right of the 33K resistor and 47 pF cap in parallel, near the center of the drawings.
GTD