Fender Twin UL > AB763 (re) build.

[pdf64]

It's worth bearing in mind that the whole chassis will tend to run somewhat hotter when buttoned up inside the cab, than when it's out on the test bench, and that heat can cause problems to manifest.
And that the AB763 mod will put more stress on the power tubes than the original 135W circuit.
Good tough power tubes are needed in there; if they're gassy (eg due to previous redplating), grid current can rise, and end up in them being prone to redplating.
The proof of the pudding is in the eating.

[olddawg]

It's worth bearing in mind that the whole chassis will tend to run somewhat hotter when buttoned up inside the cab, than when it's out on the test bench, and that heat can cause problems to manifest.
And that the AB763 mod will put more stress on the power tubes than the original 135W circuit.
Good tough power tubes are needed in there; if they're gassy (eg due to previous redplating), grid current can rise, and end up in them being prone to redplating.
The proof of the pudding is in the eating.

Also... unless you are a purist... there is nothing wrong with including a whisper fan in the cab. Many times I’ve had to put a house fan behind the occasional amp on stage...