I'm going to do a dedicated OBA thread for the MGB.
I've been futzing about with this since June, still waiting on some back ordered parts, so the urgency hasn't been what anyone would call "on point".
That said, I worked on mounting the air tank today.
I chose a seamless aluminum tank, 2.5 gallons in size. It fits perfectly in the cavity under the drivers side formed by the sliders, frame and arc under the seat. Its small enough to tuck up high and guarded.
I decided the best way to hold it there was a set of custom brackets that mount in 8mm Rivnuts on the frame.
York 210 runs to a two and a half gallon tank mounted where the spare tire used to be. Airlines run through the chassis rails to a high pressure cut off switch, regulator and coalescing filter mounted in the second battery tray along with a standard quick disconnect.
Powered off a 7. 5 amp fuse in my aux fuse panel controlled by a dash switch.
BTW, you should ask nicely and use the magic word.