Hi Sam,

Congrats on the bike. It's a big task to take on an MC18. They are old and parts are hard to find.

With the engine I'd recommend at least doing a compression test and checking the condition of the cylinders by either pulling the exhausts off and looking up the exhaust port or, removng the heads. It would also be a good idea to remove and clean the power valves.

Be a good idea to take the carbies off, dissassemble them and give them a good clean and new gaskets. Ultrasonic cleaning is great for carbies if you have access to it. I also find Threebond Petrol Engine Conditioner is really good for cleaning carbies. As Lesviffer said, it's possible you may need new float valves as well. They have a rubber tip that can perish leading to fuel leaking out of the carbie bowl overflow or even into the crankcase.

With a bike that old it's always a good idea to tear down the brakes and fit new seals and brake fluid at the very least. If the brake pistons are pitted they will need replacing too.

Sounds like your suspension front and rear is shot. You may find you don't only need new seals but things like new bushes etc as well. Some people rebuild their own. I find it easier to just remove it all and take it to a suspension specialist. Won't be cheap though.

Although there is a lot of disagreement over it on some forums, I have repaired rusting tanks before with a tank liner kit such as Kreem Tank Liner with good results. The kit contains an etcher that removes the rust and etches the metal and then you apply the liner. It's really important to follow the instructions exactly as you can mess it up otherwise. It's also one of the best paint removers I've ever seen too as a warning.

Good luck with everything mate.

Cheers
Jim