What is the value on a set of re-buildable  57 G heads?

IMO the value of used heads depends upon:
- the existing condition of the deck and combustion chamber surfaces (pock marks indicate corrosion from condensation moisture; pits can cause pre-ignition problems),
- the thickness of the pads adjacent to the exhaust ports and spark plugs (indicates whether heads were previously milled and if so, how much) and
- whether the G heads are posted or unposted. 
Another consideration for the purchaser is what they are looking to do to put your heads back into service.  Are the heads bare castings or do they come with:
- use-able valves (valve margin thickness factor; can they be reground or must they be replaced)
- springs, two piece valve spring retainers, and keepers
IF the heads are bare you can see the condition of the existing valve seats and IF replacement seats are required because of seat regression.

The value of your particular heads can also depend on their availability in your location and for the buyer outside your area, how much will the shipping cost be.


NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Are the heads posted or unposted?  Posted heads can be safely milled more than unposted heads.

Lorena, Texas (South of Waco)

Thanks they are non posted and look to be very good ,1" on the block and all chambers are rich burning black and sooty. All valves are in with beehive springs. Also appears to have pro porting at one time. Where the gasket is pealed back appears very shinny looking like a fairly fresh surfacing. No hardened seats though.
 

Where are you?

CA.