suggestions on shielding a reverb tank in a guitar head

Recently given a broken Fender Dual Showman(1980ish red knob model).  It needs a new cabinet which I am currently in the process of making.  It also needed an electronics overhaul which I did to get it working. It's loud, beefy and sounds great.  However I noticed that when the reverb is cranked up,there is induced hum from the power transformer.  This is purely from location of the reverb tank as when I moved it farther away the hum dropped in volume. With the tank closer to the power transformer then hum raised in volume.  I am wondering what would be the best way to shield the reverb tank?

I wonder if it is the transformers in the reverb tank itself causing the issue or the fact there is not enough shielding on the reverb tank.

Is the reverb tank chassis actually connected to the amplifier chassis?
Don't assume. Check it.

A friend of mine had a 1966 Vox Cambridge Reverb with the same problem.  I fiddled with it for a while and realized that if I rotated the tank 180 degrees most of the hum went away. 

Also, on other units, I changed the RCA cables to higher quality cables which helped out quite a bit.

Buy new RCA cables & wrap bubble wrap around the tank & put it back side the vinyl pouch, stopped the tank in mine buzzing & humming ;D

The springs start to loosen up over time & cause a lot of hum & buzz as well, you can tighten them up & refit them but be careful not to break the transducer? or whatever picks up the signal.

I made new RCA cables out of Belden I had lying around and gold connectors for the audio file look. It helped. The Reverb tank is at the bottom of the box and not connected to the amp chassis  ground other then by cable.  I am redoing the wood on the head so I am going to move the tank farther away and then line the bag with foil for shielding. I Suspect that it's just a matter of location location location at this point as the head is 10 inches tall. I have moved the tank around in all sorts of configurations and the best I can get is minimal noise. But it is still there and enough for me to be annoyed. Hmmmmm. Maybe the hum is not 100% escapable?