You might try these guys: www.aacncclub.com Even if they have no L6-specific info, you could bet that if the metalurgy was the same for big and small blocks of a given year, then the inlines were probably made of the same stuff.
I/I #4101
'71 GMC Jimmy 350, sm465, np205,3.73 posi.
'68 C/10 Stepside 292 (.030 over) Offy Intake, 500 CFM AFB,Clif headers, sm465, 3.73 posi.
'67 K/10 454 project.
'72 K/5 rolling frame project.
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