Anyone with experience in swapping the auto climate controls in W123 300D for the 240D's manual and more dependable system?

Both 300D's I've owned, an '80 non-turbo with the ever failing CC servo and current '85 300D with auto CC just never seem to have the right temp/blower setting although my tech says they were both operating at factory spec. A/C season and winter not a problem but spring and fall it runs me nuts trying to find the right combo of settings. I'd really like to be able to adjust the temp and blower to my specs rather than those of Mercedes.
I'm sure there would be a lot of vacuum replumbing but unsure about the hardware swap.