440 vs. stroker 408 build?

The weight difference between a 408 (small block) and a 440 (big block) is great enough to where you may want to change your front suspension to accomodate the additional weight. If you choose to go that route, the cost savings would be minimal at best... possibly even more costly.

But if you want to go fast in a straight line, and not too worried about handling, the 440 is an option. (as is a 426, a 400 or a 383) Don't forget that you may have to do a lot of cutting to fit the big block in there... depending on what accessories and type of exhaust you are planning to run on the car.