Juice:
I think you are confusing three different gear geometry terms. Pressure angle, helix angle, and pitch are different and independent characteristics.
First, pressure angle refers to the shape of the involute curve which defines the tooth geometry. 20 degree is most common, 14.5 is old school. Pressure angle can be anything for custom designs but is standardized to 20 degrees for ease of manufacture, inspection, etc.
Helix angle refers to the twist of the teeth. It's probably about 30 degrees for stock inline gears.
Pitch refers to the size of the teeth. It is number of teeth per diameter or diameter per number of teeth if metric. I would have to look it up to be sure.
Does that help?
Blackwater: Inline thrust plate clearance is about .004 inch for a stock setup. This is all the cam movement allowed. You can easily alter this figure if desired. Oil pump will continuously draw the cam rearward so I'm not sure how much effect on timing you might see.
