Depends whats the problem, knock like rod knock, then you need new rods at the very least. Count on refreshing up the bottom end with new pistons and rings, possibly an over bore and a new head gasket if you still have stocker as you cant reuse them. Also would be a good time to go forged internals if you have plans to make over 500hp if not a stock rebuild would be fine for most of us, arps would be a good idea also.... Cost varies on a lot of things, who you go to, how much you get done, how much you do yourself... Just my 2cents.