Yes they are . They are the Late Fuelly heads with the bolt holes in the front . Chevy used them on 1969-70 350-300hp with the 1.94 / 1.50 valves . And on the 350-350hp-370hp L-T1s and the DZ 302s with the screw in studs /guide plates and 2.02 / 1.60 valves . They have 64cc Chambers with flat top pistons on a 355 with a 0 deck you will have 10.25.1 C/R . I have a set with the 1.94 / 1.50 valves in real good shape . COOL