For engine info, either get one of a number of books that have these codes explained, or there are one or two good websites that have the same info. I will get one and post it later. One set of books I have is "American Car ID Numbers, 1970-1979" written by Cars and Parts Magazine (ISBN 0-87938-518-9) Amazon, Borders or Barnes/Noble can order it. There's also one for 60's as well.
The best reference you can get to figure out what you are looking at on a Corvette is the NCRS pocket guide for the particular year or series. This I purchased thru Dragich. When I was looking for a 65, you wouldn't believe what I found on supposedly "numbers matching" cars, or rather I didn't buy because of that book.
If the engine is from a 74, here's the codes-
CKZ- L48 manual
CLB- L48 manual, California emissions
CLA- L48 auto
CLC-L48 auto, California emissions
Also, the last 5 or 6 digits of the VIN number should be stamped on the block pad after the three letter code above, if it's original.
If you can get the engine code from the car, post it and I can see if it's out of a 70's vintage. Or at least try.
One other thing to look at is the body number plate on the left front door post by the windshield. THis tells you color, interior, trim, etc. Again, a way to figure out how the car started life.