> First a stupid question: is the x at the end of L- 49x there to avoid putting L-490/495 every time rather than being a separate model? I know this is probably obvious to everybody but me but I just wanted to check.

Where the solution lies in either a 490 or 495, the solution is a 49x.

> However, I also seem to recall Bill saying that when P-90s were first made they were around 6.4H.

The simple answer lies in the fact that 495s are not P-90s, so what applies to P-90s does not apply to 495s.

> As I dont know what vintage PTs pups were I wondered if a 4.8H(N) and 6.4H(L) might be a better bet.

On this logic, one would end up selecting two 6.4s.

You need to choose based on the whole equation.

While being higher output, the 64/48 combo is also darker than the standard 48/36 Gibson combo.

With your tonal objectives, and assuming youve got a mahogany-bodied SG, currently fitted with HBs that you want to retrofit with P-90esque pups, I suggest the 48/36 combo (with a change to 250K audio-taper pots).

Remember, you can always turn up your amp for volume, and you can easily reduce treble, but not add it. Also, don't forget that Townsend's tone is largely in his fingers, and his rig, the room, or lack of, and recording techniques, all colour the tone.

Aide toi et le ciel taidera (Aid thyself and heaven will aid thee)