I can speak to the master volume...it works really well with this 1987-style circuit and is ideal for knocking some decibels off. It can work down to 50% before things get fizzy. With that said, you won't get bedroom/late night volumes even at 50% when you're dealing with 50 watts. 30 watts would be much easier to tame, IMO. And use some 97db speakers.
Thank you for the reply. I currently have a 1960BX cab with Heritage Greenbacks, and an early JCM800 straight cab with G1265s.....and would like to soon have a Petersen 4x12 as well. So yes, I have nice, relatively inefficient speakers and good cabs to use. The goal is to have one foot in Malcolm and one foot in Angus. Soul Stripper, Back In Black, Ballbreaker, Stiff Upper Lip. That IS Marshall tone, in my book...but I realize there were likely several different Marshall amps used across those four albums.
So, my thought is to grab a 50w amp like the Lead 55 or Club 40, and go from there.
If you want to have one foot in lead spec (Angus) and one foot in bass spec (Malcolm) go with the Club 40. 30 watt option and a master volume with those inefficient speakers and you should be all set!
The other option is to get a lead spec amp (1987) and have it modded with Bass/Lead and Shared/Split cathode switches, giving you the option to choose what tone you want that day. I did that with a Rockitt Retro JMP50 clone and it was lots of fun. $1300 for the amp with the master, $250 for the mods, plus some shipping. You'll come in well under $2k with a real versatile tone machine.
My 1980 jmp 2203 does those tones easily. SG sounds like Angus .....i mean spot on, Strat sounds like Blackmore. .well...close enough for a tribute. Should imagine a Gretsch would do Malcom no problem.
The OP might already have or had a stack of vintage Marshalls, but if he hasn't he really should consider a 2203.
Mine does have the master, although after much trial and error I've decided I don't care for it that much. I'm currently using the master to just take the volume down a tiny it, and then a Rockcrusher attenuator to tame it. That works much better than just the master volume alone.
I also don't think the amp works well with V30's (no surprise there).