I really enjoyed reading your original post and love the thought of bringing a nice piece of vintage hi-fi gear back to life. Well done!
You are about to step onto the upgrade round-about... You may wish to take a step back and have a think about short cutting that journey. A $60 MM pre-amp may seem like a good deal now, but it will be wasted money in 6 months time. My advice is to save, go slow and buy something that will really add value to your set-up. Take your time and do your research.
Forgive me if this is too direct... If you want to stick with your Grace MC cartridge, ditch the SU transformer and go with a MC pre-amp. There is a Tom Evans MC pre-amp advertised in the classifieds for $800. This is a great entry level MC pre-amp at a great price (you need to ensure the gain of this pre-amp matches your cartridge). That will simplify your setup.
Ditch the AVR. Buy a vintage transistor amplifier (Sansui, Kenwood, Pioneer, etc) approx $500. Not sure the speakers you are saving for.... The source and the speakers are the critical bits.
I've been through a similar journey. My big moment was playing a record through a fully analogue system. It sounded wonderful, I've not looked back since.