I lean towards keeping powerplant and chassis in the same family but don't hold it as a hard rule. I've always been enamored with the Volvo P1800. If my lottery tickets ever hit I'd buy one. Initially I thought it'd be a LS candidate but then I saw these guys who pimp them out using a Volvo powerplant. Looks perfect and i'd go to the bought, not built family for it.

https://www.cyanracing.com/