Vacuum reservoir for power brakes

You said that was a solid-lifter cam right?
Do I recall .016/.016 lash?

I think I would just lash the valves a lil looser and see what happens. Say .020 intake/.024 exhaust This will make your 285cam behave like maybe one cam size smaller, with a lot less overlap and therefore idle with a higher vacuum. Just be sure there is room in the Scr to do this without getting into detonation.
This combo also wants bigger gears and a looser TC. The looser TC allows the engine to spool up before moving out. This slight delay pops up the vacuum; and if the booster vacuum has fallen off from say an extended idle-time, now it will jump to attention. So now you don't really care about idle-vacuum, unless your booster is just not working right;that's another story. In my experience, at low vacuum levels,the dual-diaphragms do not work as well as the big singles. Otherwise they seem to work fine.

Ok so the Summit site says FTH ,not solid, so I guess that ain't gonna work so good with hydraulics.
Or will it? You can run Rhoads on those lobes and get a ton of torque at low-rpm. Or you can run anti-pumpups with some lash added. Some HD lifters with circlip retainers are already APs and being an MRL engine, I suppose you may already have those; IDK.But in any case, adjustable gear would be required