Keith, I recently sold a core set on our local Phoenix Craig's for $450. They were clean, but bone stock and in need of everything. Never been touched that I could tell.
I think you'll be able to pull $500 without much trouble. Or keep them for the 70. You may need them one day. I'm still running one set in my 67 GTO, and two more sets are on my shelf.
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Eric "Todd" Mitten
'74 Bonneville 4dr Sedan (455/TH400/2.93 open)
'72 LeMans GT (455/M-13/3.23 [8.5"] posi)
'71 GTO Hardtop (400/TH400/3.07 12 bolt posi)
‘71 GTO Convertible (455HO/TH400/3.23 posi)
'67 GTO Coupe (455/ST-10/2.93 posi)
'67 Tempest Wagon (428/TH400/2.56 posi)
Deuteronomy 8:3