Congrats on getting into vinyl and upgrading your system. If you want a tubed power amp, take a look at the old Dynaco ST70 models. They have a tremendous cult following and the kits are even being reproduced today. You can get any part one needs or tweak it in hundreds of ways. The best part is that they're pretty affordable. You'll see them go around $400-$700, depending on condition, what it comes with, etc. There is a chance you'll have to replace some of the innards. Back in the 1960s, the capacitors and resistors weren't anywhere as good as what we have now.
You might also want to look at the older EL34-based Conrad-Johnson amps. Those are the MV45, MV50, MV52, MV55, and MV60. I've seen them sell between $500 on the low end and $1,300 or so on the high side. If I recall, I paid around $700 for a MV52 a few years back. It's been a great amp so far - no problems whatsoever and it'll run all day without breaking a sweat. It's not the last word in resolution or speed, but it has a very listenable, pleasing and effortless sound that I've always enjoyed. Also, these were built in the 80s and 90s, so they have modern caps and resistors inside. If one does need service, Conrad-Johnson is still around and will repair anything they've ever made.
You'll have a variety of preamps to choose from. There are matching models from Dynaco and Conrad-Johnson if you want them, but there are many to choose from at all sorts of prices. I'd look for an older model with a built-in phono preamp.
As for speakers, well, there's a lot out there. You should pick speakers based on your musical tastes and room size. You're going to find a huge assortment of speakers out there, and it is also possible to build your own from scratch or kits. Please let us know what size of room you'll run them in, whether you'd like bookshelves or full-size, whether you'd be open to having dipoles, and anything else that matters to you.
