GP crank taper angle?

Does anyone know the angle for the taper along the edge of a GP/dl crankshaft? I watched a good friend / mentor measure one yesterday using an edge finder on his milling machine. We calculated 4.25°from start of the taper until end. It was measured 3 times and calculations checked each time.
Can anyone confirm 4.25° is correct? Does anyone have access to blueprints for GP/dl cranks--or any other useful information--that confirms or contradicts this angle?
Asking for a friend, seriously

Can anyone confirm 4.25° is correct? Does anyone have access to blueprints for GP/dl cranks--or any other useful information--that confirms or contradicts this angle?
Asking for a friend, seriously

