This might be a bit much to do. It would involve lifting all grounds to chassis and tying all previous grounds together by running a master wire across chassis, then putting a cap and parallel resistor from B- to chassis. There would be the possibility of inserting a wiring error or other problem but it could be done. I believe you have a number of tube socket terminals bent over and soldered to chassis that could be troublesome to work with.
I have "fixed" hot chassis radios by making sure that once back in the cabinet, there is no part outside that can shock. You have already put on a polarized power cord which helps. You can get nylon bolts at the hardware store which are plenty strong enough to subsitute for the chassis screws that go under the cabinet. OK to use metal washers with them. If you don't have a back for this radio you can make one from 1/8" masonite with ventilation slots cut top and bottom for proper convection. When the knobs are back on there will be no metal parts exposed that have anything to do with the chassis and the radio. Some AC/DC radios were indeed "out there" like a lot of products back then (fans you could stick your finger into, cars had no seat belts or collapsable steering columns etc. etc.) but I always say that today you can still get shocked if you want to by sticking a fork in the toaster.
Attached shows a cabinet back that I drill-pressed and jigsawed from masonite.
