Sorry I forgot
I would drain the caps.
Snip the transformer wires close to the voltage selector (leaving a bit of wire colour). Unsolder wires to mains switch and earth point. Unsolder heater wires from V5.
Lift tranny reorientate and reroute wires taking care to use grommets. The primary wires (that go to the voltage selector are in the corner hole a the front) the others will be self evident on their alignment.
You will then hook the wires up one at a time colour to colour by removing the bit you left behind as a marker and cleaning the excess solder off with a solder braid (or solder sucker if you prefer) you will needa decent soldering iron ( I have a couple of Wellers with different sized ends which work well).
Should be easy. Worst problem will be if none of the holes line up to drop the bolts through (and use Nyloc nuts or lockwashers too).