Welcome. There are allot of places to find new 550 parts on the web, there is a ton of new and used parts on Ebay motors motorcycle parts by year, make and model.
A shop manual should be top of the list.
A complete set of engine gaskets will be in order for that leaky head , the 2 O rings and a head gasket and all top end stuff (except the pucks are sold separately) and they do come with the jug base gasket. Think you won't need the lower end gaskets? You'll need them too when you go through the clutch and find that it doesn't come out in one piece, and the points covergasket is usually messed up from people putting them on wrong...so it's around a hundred and some change for that, well worth it. I started out using Honda gaskets and found that they get pricey one at a time and it usually turns into a waiting game for separate parts.
What ever electrical parts ,are available in after market if not in honda stock any longer. has the harness been butchered? Amazon has aftermarket harness for just less than $100 and aftermarket anything else you could want to get it going.
Shop manual for the second time, it's that important that you have the information you may need. It's here on line but I like the book version at the scene so I can grab it when I need it .
This place is full of great people , generous with knowledge, friendly, and want to see you succeed with your project . post your build , take plenty of pictures and ask questions , show progress ( pics, like them lots) and notice that there is a search button for questions that can be answered without feeling embarrassed but guys would help you and not make you feel embarrassed anyways.
The 550 is a nice machine , easy to work on , since it's your first one that you are helping a 15 year old with it should always be FUN and a learning thing that brings you both closer, and did I say FUN .....that is the key . Lot's of pics please so we can see your progress.
