First - I hope you are hiring a marina to professionally drop the mast with a crane, it is way to big (in my opinion) to be handling yourself.
1 - take a picture and take notes on how all the connections are made in the bilge. Test each connection in advance to be sure you understand them.
2 - the marina (or you) will run a messenger line through the mast step tube when withdrawing all the mast wires from the mast support tube. This will easily allow to re-feed the mast wires back down the mast support and out the hole at the bottom when reinstalling the mast. The wires are about 6 feet long.
3 - I strongly recommend that you take this opportunity to replace the four main sheaves (2 back , 2 forward) supporting the main halyard, topping lift, spin halyard and jib halyard (unused due to CDI furler self contained halyard). They are now 30+ years old and will disintegrate any day (one of mine did at 25+ years. I had to remove the crumbling remains and run on the bare axle for the rest of the season). See my post on the part number to order from US Spars.
4 - I replaced my anchor light, steaming light and deck light fitting- all at this time. You can still buy Aqua Signal exact replacements. There is also no better time to put in an LED anchor light bulb.
5 - I did not replace my wiring as it all seemed OK, but you should inspect and consider that as well.
6 - If you plan in a future spinnaker, you may wish to consider adding a spin block to the spin bail with a messenger line for the spin sheet at this time.
Good luck with it.
Andre