1-8-4-3-6-5-7-2 (counterclockwise at the distributor) 1-8-4-3-6-5-7-2 (counterclockwise at the distributor)
18436572
1,3,7,2,6,5,4,8 Counter-clockwise.
see link
the firing order for a Pontiac 400 v8 from 1967-77 is 1-8-4-3-6-5-7-2
1-3-7-2-6-5-4-8
If this is a 400 cu inch motor the order is 13726548. If this is a 460 cu inch motor the order is 15426378. The distributer rotates counterclockwise
1 8 4 3 6 5 7 2
1-8-4-3-6-5-7-2 distributor turns counter clockwise
Chrysler didn't have a 400 Cu In motor in 1963. The 400 didn't come along until 1972. So with that in mind, I suspect you either have a 383 or quite possibly a 400 that someone swapped in. In any event, the firing order for all Mopar V-8's (with the exception being reverse firing marine engines), is a counter clockwise rotation of 1-8-4-3-6-5-7-2.
The firing order for the Pontiac 400 engine is that the small block powers the big block.
18436572 clock wise
265, 301, 307, 326, 350, 389, 400, 421, 428, 455 all have the same firing order 1,8,4,3,6,5,7,2 the 2.8 firing order is 1,2,3,4,5,6