How to tell what year a 351W is?

My dad has a 1964 Ford Galaxie 500. It has a 351W (not the original motor to the car). He was told its a 1977. But recently he wanted to put spark plugs and wires on the car. They where the wrong size. Then they told him when he returned them to the store that a 1977 would not have a points distributor. Is this correct?

I guess you have the18mm plug heads pre1975., but after 40 some years these 69-74 heads could be on any 351Windsor block. But let's say they're on their original block look for block casting number if it starts C9 it's 69-70 or D1 71 up to.in your case 1974. The year the Duraspark ignition became common in United States…
but I've seen late 80's Mexican market Ford trucks with point ignitions… Thought i'd toss that into the mix… Put in the same brand and# plugs you removed, measure the wires and buy the same length or size as necessary… Save the info for the future

how to tell what year the 351W is