Yay, new 4x12. I have always wanted a good 4x12 for the demos and reviews I record, they just sound better IMO for recording and I picked this Marshall 1960B (JCM800) 4x12 with G12T-75s and I use it with my JCM2000 and 1959SLP and it sounds RAD!
I want to try the WGS Veteran 30s which apparently are like V30s but without the massive mid range which I cannot stand. I may try them mixed with the G12T-75s
Mesa c90 or cl80 is another good mix with t75 if you're not wanting to add the mid-spike of the v30.
K100 will add fullness over the entire spectrum. Extra thump in the lows, fullness in the mids and smoothness in the highs. Great speaker to add massive body.
Avatar Speakers usually have them discounted (and they stock them in 16ohm). $120ish IIRC