Re: 5150/6505 owners
They are sort of descended from a 'rod Marshall sound, but the execution is still quite different. There is massively more body, punch and grit, more 'modern' flavour and feel. I don't mean that with '80s chops, gutar touch and suitable gain they can't produce something like that, they are just not '80s by nature.
My best bet would be a cheap but awesome RnR workhorse Origin 20 head with a dedicated booster pedal. Also, the mini Peavey 6505MH or the EVH LBX heads are worth checking. Or a tiny power amp and an AMT S1 / S2 preamp pedal that is voiced after the king of the era Soldano SLO100 head - but that's a whole different story.