Ice Man,
Steve offers just the overflow tubes for a lot less than the whole package.
I will say the whole package makes a noticeable improvement on how the C10 runs; worth is in the eyes of the rider

For hydro-lock, two things have to fail: The petcock has to leak, and the float valve has to leak (or get stuck).
The first you've already experienced. Since there is not a real fuel filter, there risk that a float valve will leak or get stuck.
I've heard others say that the rebuild kit is not very good, but I used one when the bike had around 25,000 miles, and it lasted for about 40,000 miles, at which time it started leaking again. I used another kit, but only rode the bike for a few thousand limes after that

I used the kits that are sold by Murphskits.com
I'd say use a rebuild kit to get better confidence, and get the overflow tubes installed.
Jorge