Im trying to budget build a pair of hp 500EFIs one needs a cam and they both need pistons and bored. Im trying to do this as cheap as possiable but I dont want to skimp on the lower end Pistons from my engine builder are really costly . I found another supplier thats trying to talk me into a 6.385 rod and a probe piston. He said I will gain lots of performance.and the rods and probe pistons are the same price as JE Pistons.The other question I have is about the cam, I need to replace one and for a set of cam and lifters to factory spec is alot of money almost as much as replaceing both of them with comp cam componets. I need all of this to work with the stock efi computer. becuse reprogramming is 700.00 or should I just bite the bullet and get it done? I appericate all of the help

I can't speak on the rods, but the re-cam & ecm program isn't that big of a deal. Many have went with the Crane" 731" cam. There are tons of them out there (programed ecms) so finding someone with the tune shouldn't be difficult nor that expensive.
Check mefituning.com. Ben is a really smart guy when it comes to tuning ecms and building motors.
He will shoot you straight on both price & reilability.