Theres are goreat boats with lots of miles under their keels and make comfortable live-aboards.
Other than the stove/oven burner replacement,the CNG to propane conversion other problem is a proper locker for the cylinder and one of the stern lockers are typically used since they are easily vented. Running hoses is a pain in the ass but doable with lots of patience.
you can replace the rigging yourself and save a few bucks if you know how to swage but it sounds like you might be better off getting an estimate from a few riggers - should be around $2000 tops and you won't save that much diy.
The cost for replacing all running rigging can vary depending on what type lines you choose between $1000 - $1500.
The elec halyard winch is around $3000 plus a few hundred more for cables, breaker, etc and a simple diy project if you know/learn how to do the wiring in which case you'll save probably $500 on labor.
the other stuff is mostly labor depending on how bad the interior is and what type heater you want.
In general, if it's that badly cared for cosmetically I'd be more leary of what latent problems might also exist