Random AC question

Okay. So I'm getting ready to put the Magnum I built for my 67 Dart with air conditioning. I have never done a motor on a car with air before, so I have a couple of questions.
Is it safe to just disconnect the lines on the A/C ? Will it damage anything not having freon in the system while I'm putting the new motor in? Is there any special prep that I have to do? Should I disconnect the lines at the fire wall, or just pull them off the compressor? The AC still has the original R12 in it and the a/c wasn't it's normally ice cold last year, so I'm assuming that I'll need to recharge with R134 this year anyway, which by reading stuff on here, will need replacement of the drier anyway.

I've considered just unbolting the compressor from the block and moving it off to the side, but it seems like it'll be a real pain trying to put the new motor in with that in there.

Thanks for the advice.

Doug