I was offered a set of 471 heads when I picked up a 292 this past weekend.  I do plan on building a blower motor out of this 292 and I know the 471's are good heads for 7.5-8.0:1 compression, however this set of 471's have the sodium filled exhaust valves; which I have read is a hassle since guides have to be replaced when replacing the old valves with modern SS valves.  So my question is what is a set of these heads worth?  Also, would it be worth my time messing with this set since it has the sodium filled valves?  These heads have been rebuilt and have been sitting on a shelf for 20+ years.

Thanks for any info,

Rex