There are probably two issues: 1) knowing where they align, 2) getting them there in the limited space.
Look at pics, 48, 52 and 56 in the incredibly well documented DIY below. That seems to show that the there's an empty pin maybe a quarter clock-position off of the flat. That matches up very well with the attached pic.
http://www.peachparts.com/Wikka/W123Evaporator
You might be able to cover that unused socket with electrical tape to make it the new "key" that will align with the dash. But you're sort of betting that the tape will stick, you won't push it in, etc etc.
For a permanent fix, I'd suggest getting a new plug from a pick-n-pull. Digital photo of the wiring prior to disassembly would be wise - and notes on the wire colors on the donor and the repair plugs.
For a temp fix, and to make it easier to align, I'd pull the steering wheel. Put a paint-pen stripe on the unused socket on the plug, put a corresponding tick-mark on the gap on the cluster, line them up, and carefully test. Then re-assemble.