Big Block Dipstick Problem

[dan468]

I needed a dipstick for my 68 with a Mark iV big block transplant. I bought one from a local parts store and the oil would not register on the stick. I pulled the tube and placed it on a similar oil pan laying around the shop. I filled it with 6 quarts of fluids to see where it would come to the dipstick, still no luck. My question is, how much fluid should be in the oil pan? Should the level surpass the sump? Do I need a better dipstick? Here's a picture of the mock up with 6 qts and it doesn't touch the tube or stick.