I think the schematic I derived the TAN schematic from said 275V but you are right, both the Weber and the Mojotone transformers are 330V. That should be the correct voltage. I will fix that, nice catch, thanks.
A smaller transformer will change quite a bit in the amp. All of the voltages to the tubes are calculated based on the 330. Going lower in this amp probably isn’t too big of an issue. But the tubes will have less gain, the onset of distortion will change and there will be less overall power. Probably would do some bias calculations to figure out what it would do exactly though.