One of my dad's friends stopped by the shop today with some 427 car heads that are dated 1967 and the casting numbers are 3904390. Would these heads be worth getting for a future build. What should I offer him for these heads?

390 heads were used on 390 and 400HP 427 Corvette and 396 Chevelle, Camaro and Chevrolet. Oval port, not bad street heads but not particularly rare or valuable.

Here is a set that has been redone.

http://cgi.ebay.com/ebaymotors/BIG-BLOCK-CHEVROLET-HEADS-3904390-BBC-CHEVELLE-IMPALA_W0QQitemZ300408756629QQcmdZViewItemQQptZMot ors_Car_Truck_Parts_Accessories?hash=item45f1c1d99 5