Neck, tuners, neck plate, scratchplate, control plate, knobs and pots. I still have the original pickups in a drawer, they were really not bad in the slightest, but the DiMarzios are a massive upgrade.
Get in touch with Guitar Guitar in Birmingham https://www.guitarguitar.co.uk/stores/birmingham/ if they're anywhere as good as my local GG, they should be able set you on the right path.
If at all possible, get out and try them, sounds obvious but one might have just the tone you're looking for, which is difficult to judge remotely (but not impossible with YouTube, etc). Purely from an aesthetic perspective, the Marshall looks ace.
The connections may look OK, but it may have a dry joint or the switch has failed (why changing strings would accentuate this is beyond me). Do you still get the classic in between sound on position 2, or is it just the same as position 3 (middle pickup soloed)? Either way, resoldering the connections from the bridge pickup won't hurt and may solve the problem).
I'm a huge Peter Gabriel fan and if there is one track that is my 'favourite song of all time', this would be it. When I was asked to play bass and be part of a collaboration to create a lockdown version of this track, I didn't need to be asked twice. I'm immensely proud of this and it was an honour to work with so many talented folk (please check the description and the end credits). For a short time, I get to be Tony Levin (one of my bass heroes), complete with hammy, deep bass, vocal part.
The only experience I have of any of that list is Focusrite; I have a Solo. I recently did a collaborative effort where I played bass and I used my Sadowsky preamp pedal into Tech21 bass amp sim DIed into the Focusrite. The results were very, very pleasing.
Les Paul was a massive advocate of low impedance, which led to the eye sore that was the Recording Model. Weird that the opinion of one of the electric guitar’s pioneers didn’t seem to catch on with the guitar playing public. Zakk Wylde also used active pickups back with Ozzy and Pride & Glory (he may well still do so, I don’t know).
I think I heard Dreamboat Annie for the first time in ‘76, to be more specific the track Magic Man. It was on the radio in Spain and both my dad and went, “Wow! Who is that?” The first Boston album would be up there too.