Hard to say what they might do for your system/room. I like these particular Raytheons in the right setting, but they are typically an occasional use tube for me. In this set, particularly with these warmer inputs, they are awesome. The bases flare out from the bottom, the relatively fat bottle glass set into the wider top part of the base. They have dual top rectangular getters on the sides.
There are other Raytheons (I believe 50s), fat bottle, medium height, standard bottom, dual top rectangular getters, and these tend to sound very slightly less solid, and little warmer in the low mids, with open and fresh upper mids...interesting too. It looks nearly identical to a pair of Tungsol I have. Seems that at least in the 50s, with OB3s and 5U4GBs I have, that Tungsol and Raytheon are the same.
I really like 5U4GBs as a choice, and since they can be had inexpensively, I have a number of pairs. The distinguishing characteristic for me is a sort of hard to explain, spacious and textural midrange.
The Sylvania tall bottles I have are nicely balanced and lively, and a pair of early RCAs with vey long bottles and inner construction like 5U4G-ST, with no bottom mica....these are amazing in their extension, spaciousness, and transparency, but in my system, they can be demanding, needing just the right balance to warm them up a bit.
The thing I found looking around Ebay for these tubes is to look carefully at the pictures to see that they are just the same construction....same bottle size, mica, getters...as well as test scores. Then even they have different labels, you have something useful to play with.
Fun and games!