the 894 head was used on 340,s 1968 to 1970. 1971, they went to 915 castings, with 2.02 or 1.88 intake valves. the 894 head will outflow the 915.
i'vetested both sets, 894 is better. the 915 is an ok head.
The 915 was also used in 1970 it is the same casting number as the T/A, it had 2.02 valves and the intake pushrod holes were offset. I have found that both heads flow basicly the same if they have the same size valves.