You will need, minimum:
A set of properly fitted screwdrivers
Action wrench that fits
Barrel vise and an immovable object to anchor it
Rosin for the vise blocks
Set of headspace gauges for the caliber
If you're not lucky, you'll need a chamber reamer if short or a lathe AND a chamber reamer if long to set the barrel back one turn. Marlin timed the barrel threads pretty well, for the most part, but there's always an exception out there and you may have one.
The basics will run you $300-400 if new, I use a 20 ton press to hold the barrel vise and provide a little extra holding power, that's an extra couple of hundred. If you're well-tooled, you can make most of what's required. But you probably would be doing it if you were instead of asking here...
I prefer to change out the whole front section, barrel, magazine tube, forearm and all the hardware instead of cutting and fitting bits and pieces of the original. The gun can be easily returned to its original condition that way. Original CT Marlins are going to go the way of pre-shutdown Winchesters, the process has already started. So think twice about hacking on an original.
Tooling up to do this is probably not a really good return on the money spent just to do a onesie. Screw it up and you buy a new gun.
Stan S.