I removed the bypass oil system from my car yesterday and replaced the filter and oil. i checked the capacity in two locations 5qts. Added this amount and took the car for a short drive, tuned off the engine and let it sit for a few minutes, checked the level and it was above the F mark on the dip stick. What could be my problem ?

How much is it above the full mark?

Just above the H

You don't have a Fram oil filter do you? I have had the anti-drain back valve in the base model Fram filters fail, allowing all the oil in the filter to drain back into the pan. And yes, it happened on a new filter!

Full disclosure: I have no financial interest in any oil filter manufacturer or reseller. I am just reporting on my personal experiences. I am sure the problem could happen with other brands, I have just never experienced this failure except with the brand listed above.

No i used a Wix filter.

Is it possible over the years and multiple engine rebuilds my dad could have replaced the dip stick with one from another engine. What is the difference between dip sticks in early and late model 280z-zx's ?

The capacities listed on the manuals are approximate. Always use the dipstick as the final gauge. If it only take 4 3/4 quarts to fill it so what?