The amp will run probably 1200W PEP output, which is indeed 3dB more than an SB-200.
It's a really pretty amp and wish I had one now to match my TR-7, just because they'd look really nice together. One of these days...
I have put these on six meters, but in every case tore out all the HF components and just put it on 6m only. I used the TUNE cap for the LOAD cap on six, replaced the TUNE cap with a 3-30 pF vacuum variable, and wound the tank inductor 3-1/2 turns of 3/16" copper tubing on a 1-1/5" diameter form. For the input network, I rewound the 10m inductor and substitured smaller mica caps. For the plate RFC, I used the same form but removed about 3/4 of the turns until it dipped at about 60 MHz.
The original filament chokes work. The original T-R relay works, but has some loss on 6m so I'd usually sub a pair of Dow Key relays to pick up that dB or so that the original transfer relay and wiring loses.
It's not a difficult conversion, but it is a single-band conversion.
Never tried to "add" 6m along with the other HF bands, I'm not sure that would really work.
What if soy milk is just regular milk introducing itself in Spanish?