Probably not without tearing the heater box apart and re-routing the hoses, if you are going to that much trouble better to just replace the valve and be able to adjust the heat.
The good news is that if you need a new heater core, you can get one. Not all that long ago, you could not. The A/C heater core was discontinued by the early eighties, and to make things worse, all the aftermarket parts books listed the incorrect non-A/C core as fitting the A/C cars. I tried to buy one for my '66 New Yorker back in 1984, and no dice. Luckily, it's the same as the one used in the B-Bodies, which is the only reason it's available again. The temp control valve on the firewall can be rebuilt, though it's a bit of a pain to do.
Last time I checked, Arizona Parts still had a few NOS tilt/telescopic turn signal switches in stock for $180 each, which is a real good price for that switch. It's actually a GM switch because the columns were made by Saginaw. You can look up the part number on line, then search his website.
A test light and your service manual should tell you if the switch is bad. The wiring diagrams in the manual can be a bit challenging to follow. I like to re-trace the lines in the correct color marker to make it easier, or you can buy a color diagram on ebay fairly cheap.
Oké, Today I had some time to check things out on the electric problems on the Imperial.
The good:
The turn signals work front and rear)!
Still no break lights and tail lights when I put the lights on :-(
I tested the 4way flasher. It does flash but the rears are not as bright as when I use the turn signal. Is this normal?
Maybe this has something to do with the rear lights and the problems?
And one more thing: The owners manual tells me I can pull the fusebox downfor easy visebility.... is this true? I tried this and to me it’s possible....