The HV code fits two installations:
1965 Corvette 350hp 327 with theRPO L79 and a 4 speed single 4bbl Holey carb
1969 Impala 255hp 350 with a turbo 350 tranny RPO LM-1 single 4bbl

The block casting 3932388 says it is a 1968-1979 350 with EITHER 2 bolt mains OR 4bolt mains