Based on your speakers and price point, I think a used 300B is probably the most likely candidate for you. I don't think you will be happy driving your speakers with lower powered SET amps 45/50/2A3.
Another potential option is to keep checking ebay as periodically Sean Casper offers F2a amps in that price range. The Siemens F2a tube (made famous in German Klangfilm amps in the 1950's) has about the same power rating as the 300B but has a completely different sonic signature. It is a much more dynamic sounding tube with better bass. It also has a wonderful presence to it - it comes across as a much more powerful tube. What it does give up to the 300B is some midrange sweetness and a bit of nuance. Both would be very good alternatives to your OTL.
Another potential option is to keep checking ebay as periodically Sean Casper offers F2a amps in that price range. The Siemens F2a tube (made famous in German Klangfilm amps in the 1950's) has about the same power rating as the 300B but has a completely different sonic signature. It is a much more dynamic sounding tube with better bass. It also has a wonderful presence to it - it comes across as a much more powerful tube. What it does give up to the 300B is some midrange sweetness and a bit of nuance. Both would be very good alternatives to your OTL.