/6 build cost

It's all dependent on how much of the work you can do yourself. The cylinder head is the big limiting factor, as it was never redesigned for the larger 198 and 225 engines, so they have a head designed for a 170. Turbocharging though, takes a lot of that problem away, as the head becomes much less of a limiting factor with forced induction. @Charrlie_S can probably help. I tagged him so maybe he'll chime in.