Here's a list of my mods in the order installed. Tube rolling is in a separate list below.

1. VS Hum & Noise Reduction V.1 (filament snubber). (I took this out later, since subsequent mods reduced noise to inaudible anyway.)

2. High Voltage Snubber. Reduced noise.

3. Upgraded plate choke to Magnequest BCP-15 and moved old choke over to filter duty. Clarity and solidity greatly improved.

4. C4S board. Essential -- bass is much tighter and cleaner. Plus you get slightly higher gain. This was a huge noise reducer as well.

5. Upgraded power transformer to Magnequest TFA-2004 Nickel. Brought the bass up to solid-state tightness and authority.

6. Installed toggle switches between 4-ohm and 8-ohm taps. I needed this when I was experimenting with different speakers, and have since bypassed them.

7. Removed 12AT7 sockets and rewired driver socket to accept 76s. The result was a softer, warmer sound that I now realize was compensating for harshness in my speakers of the time. Since I got my 4 Pi's, I've switched back to 12AT7s.

8. Cathode parafeed mod. Greater transparency throughout the spectrum.

9. Upgraded coupling cap to Auricap 4uf. Mids and highs are much sweeter and more accurate.

Tube rolling:

2A3: Started with the stock Valve Arts, switched over to Sovteks (didn't like them at all), vintage RCA biplates (wonderful) and finally TJ 300B 2.5V meshies (best of all).

12AT7: My stock tubes were NOS GE's (don't know which year or kind). Switched to Brimar blackplates from Ebay that turned out to be fakes (and didn't sound so great), then GE 6201 5-stars (best high end) and finally Sylvania Gold Pin 6201s (best all around performers).

76: When I had 76s instead of 12AT7s I experimented with a bunch of NOS Sylvanias from different sources. They all sounded identical so far as I could tell.

Hope this helps.
Patrick