Oil dipstick full mark

For the record, I've daily driven my Barracuda for 15 years, but I replaced the slant 6 that was in it with a 318 about two years ago and had a lot of problems with it. It's my first small block and I'm still learning. From what I gathered the 273, 318 and 340 oil pans from '64-'72 are essentially the same shape. Not sure about 360s. The early ones didn't have any stampings, the '67-'69 ones are stamped 394 and the '70-'72 are stamped 294 and those don't have the nipples. I'd guess that 90% of people, if they check their oil at all, depend on their factory dipstick. So there's got to be a reason why Chrysler marked their dipsticks where they did and that should be consistent at least with a 318 and a 294 pan.

When I filled 5 quarts with a new filter and marked my stick, it actually ended up being 1-1/2" above what @Dana67Dart measured. That is a significant difference and I'm trying to figure out why. At some point I suspected a coolant leak from the intake which could explain the higher fill level, but there was no milkshake. I was also wondering if there was gas leaking into the crankcase, but also didn't find evidence of that.