I'd factor in about 20%ish for additional costs (above your base figure) in the building phase. There is always a bunch of stuff that gets overlooked or something won't work as you planned. I figured about 5K for my big block stroker and ended up spending about 8K, but most of the money I spent went into the heads. If you go with a crate motor, you've got to figure for items that don't come with the motor or upgrades you may want such as fueling, oiling. water pump, radiator, carb, intake ect. Then there's ignition, exhaust ect. If you go with an MSD ignition system and say a set of ceramic headers, then just add another grand. You can do it on a budget, just takes a good bit of planning on where you want to spend your money and what you want out of the motor!! Good luck
Matt B.