the clymer manual is pretty good. It isn't the be all end all, but you can definitely follow it for the basic maintanence.
Sounds like you are definitely on track. I would get carb kits definitely, seing as it sounds like your float valves are shot. While they are open, make sure the float heights are correct. I got a small metal slide ruler at Canadian tire for this. It works very well, but make sure you check both sides of the float. Make sure when you check valve clearances that the bike is dead cold. Leaving it overnight is usually the best way to go.
As far a runnign goes, the easiest thing to check is spark. I always start with that. Just pull the plugs, and crank her over while holding the plug against the case. Just be careful, you can get a nice comfy shock or two from this. While you have them out, check thier condition. Are they wet? If so, with what... gas or oil? Are they black and sooty? Typically you want the insulator to be a mid-shade of tan... (I believe the clymer manual has a spark plug guide near the front of the book)
After that there's fuel and compression. Compression is easy enough to check. Put your thumb over the plug hole and turn it over. If it easily blows your thumb away, you have enough compression to run. Fuel is the hardest one, IMHO, but it's more intimidating than actually difficult.
Your 78 should have keihin PD carbs. Since april, I've had mine apart 7 times, so I'm a bit of an expert on these. Haha. Make sure when your carb kits come in, you replace the o-rings underneath your pilot jet screws. I mention them because they are hard to see, they are difficult to get out, and they can cause major headaches.
Wow, I went on. If you have any questions, don't hesitate to ask!
