I don't have direct experience but the GM Parts Catalog lists it as:
1970 37 Amp - 6 Cyl. Eng. - Exc. P.S.
1970 37 Amp - 307, 350/250 & 300HP/ or 396/350HP/ Eng. - Exc. A.C.
It seems correct based on that with the L34 being 396/350 HP and you not having AC.