Verify that the dots/symbols are lined up correctly. You can use a speed square off the top of the block somewhere to give you a better visual center line to align the marks. Also note that every time you change the crank sprocket key way you have also changed TDC postions so TDC would need to be found again.
If it still doesnt come clear, sometimes those degree wheels are marked funky.
Go back to the basics, find .050 past max lift, then mark the degree wheel with a sharpie. Then find .050 before max lift and mark it too. Now look were both marks are on the degree wheel. Count each degree between the two, then divide by two. It should produce the same numbers.

Rotate the engine around more than once recording each event. Sometimes its easy to loose a bit in slack or what ever. Keep doing it until you keep producing the same results.
But remember about moving the crank keys..you gotta find the new TDC again, a bunch of people dont, its not worth the trouble of doing it then IMO.
This is why I like the cam sprocket bushings.