What fuel would a Bell Huey helicopter use in 1964?
In 1964, the Huey would use JP-4 or JP-5 . 

When fitted with models T53-L-5 or T53-L9, the Huey would burn JP-4. 
With engine variety engine T53-L11 it would burn either JP-4 or JP-5. The JP-5 type fuel was mainly used for Navy operations.