Is there a 300B or something that gives you that same sound out there with power so you have more speaker options?
In a strict sense no. Each tube type has their own distinctive sonic character. Can you find other satisfying alternatives? Yes. As mentioned above, an 805 output tube, there’s 845, 211, GM 70 , 6c33c etc. These all can be utilized for higher power SET amplifier.
All are quite capable of exquisite sound quality with good design and excellent implementation. I understand your happiness. The 300b is marvelous in proper circumstances. There are 300b push-pull amplifiers alternatives also.
Charles