What's it worth

Got the motor and trans on Sat. Popped the valve cover and oil pan. This thing is SUPER CLEAN inside. As soon as I have more time, will post pics and numbers. I did see a 4 78 stamped on the exhaust side of the block. Engine came out of a Dodge 1/2 ton shorty van. He said it had a 650 Holley on it and ran like a raped ape through the first 3 gears. His Uncle built it and gave him the van for his 18th birthday. The van body gave out and he pulled the motor and hung it on a stand about 18 years ago. It turns over with a socket and ratchet. Gave him $400 pending internal inspection - I think I'll go the additional $300 now that I've seen the inside.