Just an fyi. There is actually "KITS" available now. Vitos for example has several. They come complete with 68mm jugs, ported or not, the crank, pistons, head, domes, gaskets and all. everything you need. Of course there may be some fine tuning involved but for the most part they are bolt on and go. they range in price from $500- 1100.
I suppose you could also call it a "kit" when you piece a setup together from one place like I did. Figure of speech I guess???