If you are building a Marshall 68-72 model amp: Mallory caps are better than Sozo. Sozo standards are better than Sozo vintage.
If you are building a JTM era amp the Sozo vintage defocus and don't sound so forward.
Resistors
It's a Marshall! Everything sounds great!! The cheap stuff is great, and the crazy stuff is great. I like using way oversized resistors in the signal path,but I have never found a type that didn't work for me. Have at it. Suggest something excellent if you know better.
Transformers
I have used originals, Merren, Wallace, and Classictone. The Wallace is my favorite build. Merrens are just as good but a little harder to get. The Classictones are very inexpensive and sound absolutely fabulous as well. Never a problem with any of these, but I prefer the Classictones for late model 4 holer things, and the Wallace for JTM sounds.
Pots
Alpha. Cheap and good. Taper is fine. Buy extra 500ks on your order for you humbucking guitars.
Chassis
Good luck. You tell me.
Brian Wallace is good about special runs, but they are months between orders.
Other bits..
Silver mica is good in an amp where you want serious note definition, but awful sometimes on mixer bypass. I like ceramic disks. Micas are pointy, and ceramics sound wider and grainy is a good way. If you use mica use a smaller than total value and add a ceramic to make up the difference. Micas sound like they are pinging at a supersonic frequency sometimes in a bright amp.
Tubes.
Dood, the Mullards are all gone. Bob S. broke the last crate full. EH 6ca7, JJ 6ca7 or EL34L and good luck on the preamps. Steal good tubes out of vintage Fenders! lol