I have the exact same problem.
I have a 1970 vette, and the owners manual, and shop manual says 5 quarts.
I completely drained the block through the oil pan drain plug, I then put five quarts into the engine (one of the 5 quarts I used to fill the new filter (normal short style ACDeloc filter) the remainer of which when into the block.
I started the eninger, got the oil pressure up and took the car for a drive. . .thinking I have the correct amount of oil in the car.
The next morning I went out to start the car. . .but before I did, I decided to double check the oil level. . .and was horrified to see that I was 3/4" above the FULL mark on the dipstick!!! I quickly removed about a 1/2 quart from the block and got the level down to FULL. What gives? Is 5 quarts too much. . .or is my dipstick just way off. . .or the wrong one for the car. It looks like it's origional. . .but I cannot verify.