The simplest way to get a display for your rig is probably just to go for CAT control on your radio.
Control software can be a something free like FLdigi or similar, there are also software that can run under linux.
I have done some repairs of the 746 in the past. If it is the backlight that is causing the display to fail the fix is basically only to replace a transistor.
The original transistor (2sb1021) is a bit low rated (2A) for this use, we used to put in a 2,5A or 3A transistor as a replacement.
http://www.ka1mda.org/ham/homebrew/746/index.htmIf you go for this repair, instead of this bolt-on heatsink there are heatsinks that can be glued on with tape or two component epoxy.