[Mike Taylor 3601]

450 is last three# of 305 heads,K 1 78 is date code date is 11-17 1978
458 probaly is 450 if inspected closer. If not interested in 305 let me know 450's are what my car uses.
date code is done alphabetically ie A=Jan. B=Feb.C =Mar. and so on
usaully year has one # so you have to be able to know how to tell what decade it was made which takes a little more experience.
year was 8, has breather vent at rear of intake valley and small journal you know it's 1968,
large journal mains you know it's a 1978,(69 and up are big journal)one piece rear main you know it's 1988 (1986 up were 1 pc.rear main)
another quick check is left hand dipstick (drivers side) is 79 and earlier, right hand is 80-85 model. another quick check is small journal has 11/16 head on main bolt 1/2head on rods big journal has 5/8 head on main bolt 9/16 head on rod bolts.
Mike Taylor 3601