what do i have? junk?

2406516-5 is your casting number. If they both have that, they are a matching pair. That number is for the 383 closed chamber head. They will be good for a mild build with flat tops. You can get 9:1 plus real easy. They don't have the larger exhaust valve, but that won't matter if you stick with a mild build. If you get the larger exhaust valves put in and ported, they should support 450 or so HP. IQ52 would be better to tell you specifics. He's probably the best on the site.