[TroyBoy]

We need more info about your engine. Is it a healthy running engine that you want to upgrade? Or worn out and needs to be rebuilt? What style of Jasper rebuild, stock, or one of Jasper's hi-performance builds? If it's worn out, as pointed out, you could spend $1000 just on machine work to do a quality rebuild, with no way to do a performance build for that sum. However, if you have a solid, healthy engine, you could do some upgrades for $1000 that would enhance the performance, but reaching 400 hp for that price probably is an unrealistic goal.

Ed

This^^^. You really need to dig into the engine a little. At least pull the valve covers and see what kinda heads you are working with.