X J or TA Heads

The 915 could be a T/A head. Only if the intake rockers are offset like Tony posted AND the pushrod holes are offset drilled.

The 894 head WILL NOT be a T/A head. Most 70 340's came with the 915 casting number J heads. Some 70 340's did have the earlier X heads on them, generally early built engine may have them as to run remaining stock through the assembly line.

There are pics posted of T/A and std heads on this site somewhere regarding the pushrod holes.