questions about 840 kit

I have 09 teryx with msd, muzzy,dalton od plate, going to do clutch work possibly vforce john stage 3 build have been thinking about egine kit, don't know much about any of them, have talked to Todd at Hunter Works about a standard bore with cams. Could any body tell me what the 840 kits include, who makes them, what kind of hp they produce,what if any extras i would need to go with them besides what I already have, what is the rough cost of them, and reliability and longevity of the engine. thanks