Bob your doing better than me in breaking it back, WA doesn't show up in my references. (Sorry Jani).

Just to add a little to what Bob said, the little triangle you circled on the head is usually the easy way to tell if the heads are "power pack" or not).

Chevrolet used the short water pumps on the magority if not all their cars through 1968. The Vettes and the trucks used the short pumps longer.

Jani, keep in mind there is nothing magic about a Corvette motor. Yes they did use the better heavy duty factory parts, but these could be purchased over the counter at any Chevy dealer, and with few exceptions (the tri-power 427 comes to mind) the engines themselves could be special ordered in almost any other body style. With the parts available these days, it would be fairly simple to build the 283 you have to meet or exceed the original Corvette HP numbers. All that is really needed is to match the Compression ratio, cam size and profile, valve size and carburation.

We used to have a joke around the shop that "Every Small Block Chevy had been a Vette motor and every Early Hemi was a 392" due to the number of people who made that claim about their engines (especially if they were trying to sell them).