^ Hmmm, well, you certainly need the piston and cylinder, ring set, gaskets, o-rings, etc, but I'm wondering about the last two parts, the "head-asst cylinder", part 11002-1322 and the Head Cover, part 14090-1477?
A quick search reveals that the first part number is for the entire cylinder head assembly:
The second part is the head cover, but it's no different than the one that's already on your bike.
I'd double check with the mechanic as I really don't think you need these parts. None of the other big bore kits, such as the Bill Blue 351 of the Kustom Kraft 330 require any changes or modification to the cylinder head assembly or head cover.
If you deduct these parts from the total then you get a price that is quite close to what Trent was quoted when he asked about the 300cc conversion a while back.
Also, the head cover gasket can be reused and only needs to be replaced if damaged.