Just from my experience....don't do it if it aint leaking...wait until you have too!
I picked up a boat that had a 2000 or 01 130, that i repainted. Figured I'd clean the jacket as it had similar corrosion but no leaking. Brackish salt water use. I pulled the jacket but honestly it was pretty clean inside. The thermostat is the one that really needed a cleaning and you don't have to pull the jacket to do that...it gets a pretty good bit of deposits up there. Also pull the flush port up with the pressure relieve valve.
Anyways I did pull mine and cleaned some deposits from the water jacket but it wasn't anything major. Couple notes from my experience, those bolts suck, if they are seized in from the white powder corrosion they are small, not very large diameter and *will* snap without much warning. I snapped 3 easily, and lucked out drilling them out with a tungsten carbide dremel bit and chasing the threads with a tap...that was after soaking them, heating them a bit ( i'm sure my mapp gas was not hot enough to really help)...it was a pain and pure luck i was able to do get them out diy.
IF you do pull the jacket and the lower ones snap...you'll never get to them to drill them out without what iirc it looked to me pulling the engine off the casing...just no access to the lower ones (outside of wrench to take em off).
Clean around the thermostat and flush port and go with it. If you do pull it, your jacket will probably have some corrosion, there's a channel in there the rubber gasket sits, the inside edge can be corroded away at spots and that's why the bolts get some corrosion around them, a bit of gasket sealant will be needed (i didn't bother replacing my cover). But on an 01 motor i'd just let it ride, if it's not leaking it's nothing major...not like a bit of corrosion on bolts will leave you dead in the water and you're inviting possibly a lot more work.
The other thing is if you do pull it like i did, I used a bit of a wire brushes on drills,etc to clean deposits with a shop vac, but to this day my pisser still clogs everytime out from the left over making it's way through the system.