It seems to me that a crate engine class can do just the opposite of what has been suggested. A beginners class with the goal being to have drivers move up to the 410"s. Then when they do move up hopefully there would be some good used crate cars for sale for the new guys.
Here where I am I'd take any nonwing sprintcar class offered. They race crap cars around these parts.

p.s. good used crate 602"s are cheap around here. You could buy a good used engine every season for years and not spend near what you would to build your own engine. A lot of guys replace their engines yearly and a well maintained 602 can last a few seasons.