Good point on asking Steve Leung, there @Dogberry. I also would not underestimate the N Clayton builds- I needed something not spendy for my vintage system based on old Quads and was using a VAS Franken-Denon cartridge Steve put together. Clayton may be taking a few days off for the holidays- but offers blue Cinemags, as well as vintage transformers. There is also a guy on SHF who custom builds some old stock Altec Peerless- he used to work at Altec and had a stash.
I remember first looking at SUTs years ago when I was still running an ARC SP-10 --it had gain, but the preamp was notorious for microphony. At the time, I was trying to find the elusive Expressive Technologies unit- no go.
I use an Allnic phono with built in SUTs on my main system- readily adjustable with the turn of a knob. I like that feature-there are differences in sound based on the settings. My dumbed down approach is to look at the internal impedance of the cartridge and multiply by 10 for the load seen by the cartridge. The secondary (or output) from the SUT will be 47k.
On the cables, I do use the high end spread in the main system, but on the vintage system, use Analysis Plus -- well made, cost effective, and suitable for a system of that period.
Good hunting.