So it turns out my heads on my 427/390 have a small crack in an exhaust seat. The shop was not concerned, said they weld them all the time, and I'm also having new hardened seats installed anyway.
Before I knew the extent of the crack I searched around to see if I could find a head with a similar date. Mine are casting code 3931063 and are date stamped L-2-8, or December 2 1968. The engine was built some 10 days later.
The closest I could find was a head cast in October. So I opted to move ahead with repairing the original head.
Then yesterday I was searching eBay and found a set of heads with the same casting number cast on the SAME day as mine! Coded L-2-8
I waffled for a day or two. But I just bought them. Since I was installing hardened seats and the crack repair, I decided to have the intakes ported, as it's well known in the Corvette community that this particular head flows really well once cleaned up. But the engine builder still wants to use the original heads because they're virigns, never even had a valve job before.
So I will set these aside somewhere safe in the knowledge that I've got an original unmolested pair of heads with my original date code! There's also a clock cast in there, I'm curious to see how close in hours the two pairs were made.
