OK, so let's advance one more step:

I thought of the following mods:

1. replace OPTs with 3.3k blue.
2. replace power trafo with a 275-0-275 (or 300-0-300) 200ma secondary (270HX/272HX) and a 5AR4 rectifier tube.
3. add another SV83 in parallel to each channel.

What do you think?