I am currently looking at a boat with older model carbureted 525 SCs with Mercury Superchargers (1994 I believe). The engines currently have 505 hrs on them. Engines have not been apart or freshened yet. Curious what maintenance you guys are doing at what hours. Also how would they do on fuel consumption in a 382 SR1 with bravos? Thanks for your time and input!

Very reliable engines, but very thirsty on fuel and need 92 octane.
At 505 hrs, they need the blowers gone through and top ends done at a minimum.

did a pair of 98's couple years ago, cams were's going in them as well, had bob M. do rollers as close as possible to stock...

I would be worried about the blowers.the stock rear seals leak gas like crazy.So your bearings are swimming in gas,rotor to rotor contact from loose bearings can cost you as most parts are NLA.
Some Cams go flat as mentioned.
I read they were 1200 hour rated,with maintenance items. Like Griff said they need top end work for sure.

Mine have 250 hours (sealed also) and use pint oil every 20 hours.Run like they are EFI motors.
Thirsty, but the torque mid range rpms is strong.Sent my blowers to DMPE this spring all good.