according to Mortec they are:
3973487....71-72...350..........used on 71-72 350 LT1, 75cc chamber
http://www.mortec.com/castnum.htm
They look worthy of a rebuild to me.
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John Hutchison
Grapevine,Texas
76051
71 1/2 ton swb 307 pg
69 Jaguar XK-E 4.2 Roadster