Tubes: 1-6SN7; 1-6V6; 1-5Y3
The R300 is a more straightforward design than the R200. My guess is that it was designed to go head to head with one or more of Fender’s early Champ models.
It is similar in many ways to a Fender Champ, but unlike later tweed Champ models, it has no negative feedback loop around the output tube. The feedback loop would reduce gain, and decrease distortion. It is also different than a Champ in that it has a tone control. More features!
This is an amp that should sound just fine!