Probably not the best choice. My recollection is that fuses #6 and #7 are energized in the accessory and run position of the ignition switch. Fuses #3 and #4 are energized only in the run position of the ignition switch. Volvo uses fuse position #4 to supply the OD in later model 140s. Its not a disaster since you have a 4th gear interlock and its not like the OD solenoid could get energized while the car is parked and you are sitting listening to the radio (unless you park it in fourth gear with the OD column switch on).

It has been a while since I poked around the fuse box on my 142; however, my recollection is that the top side of the fuse panel is the load side (protected by the fuse) and as such is the correct side to come off with a protected supply