I made this very upgrade last season, when the original main halyard winch finally packed it in. I can send you some pictures.
When I bought the boat, there was already a newish Harken winch on the cabin top to port, for the genoa halyard, with organizers and clutches on both sides for genoa, spinnaker, vang, reef 1, reef 2 and topping lift. For some reason the topping lift was lead back to an ordinary horn cleat. I added a matching winch on the starboard side, with a larger organizer and a double clutch for the topping lift and main halyard, and removed the cleat. I now have genoa, spinnaker and vang to port, with reefing lines, lift and main halyard to starboard.
The mast has a formed stainless plate at the step, with "wings" on the four sides for attaching turning blocks. This would be an easy, inexpensive item to have fabricated. Did you say whether your halyards are internal or external? It's easier to change the lead of external halyards.
It's true that you will still have to go forward to hook in the tack of the sail when reefing. However, one goes forward twice every sail to raise and lower the main, whereas trips forward to reef are occasional. I really don't enjoy scrambling forward to hoist and douse when sailing alone in lumpy weather, usually in the shallow water off a harbor mouth where the incoming waves pile up! If the main halyard is marked for the first and second reefs, it can be eased the right amount before leaving the cockpit to hook in the tack. (I've thought about installing a single-line reefing system with cheek blocks on the mast instead of a hook on the boom--has anyone tried this?)
If you're worried about the length of the wire halyard, you could replace it with line. The sheeves at the masthead aren't hard to replace.
The hardware cost does add up. So does the total number of bolt holes you have to drill for the organizer, clutch and winch. If you grind out the core of the cabin top and fill it with epoxy around the holes, which you should, the job will take longer than you think.
One challenge with leading all your lines aft is finding a neat place to stow the coils and keep them untangled. The cabin top under the dodger is a good place.
Speaking of the dodger, if you have one, consider where the lines you lead aft will run in relation to the fastener buttons, and place hardware where the dodger won't interfere with it.
Hope this helps,
John