Stop measuring angles. There is NO one correct angle that is the same for every horse!!
The SOLE determines the height of the heels and the angle for an individual horse . The sole shape, bars and and the frog determine where the coffin bone is inside and where bevel in the toe should be for breakover.
When a hoof has a chance to wear down to its optimal angle and form it will wear naturally equally around the SOLE.
So we should trim to the sole, equally all round the foot. Some hooves will naturally have taller heels and a taller angle, some lower . But it will be the right angle for that individual horse
And many trimmers remove WAY TOO MUCH hoof wall. So for beginners, leave a little wall (1/4" ) beyond the sole for safety sake, nipping or rasping it to equal height all around the cleaned SOLE. Then when you remove flares and round off the edges a LITTLE it will not all be gone. Horses should not walk JUST on their soles.
Then , to reduce leverage at the toe and prevent strain in the tendons, bevel the toe a LITTLE BIT STRAIGHT ACROSS, from the sole side, at 1" inch in front of the end of the frog on a normal size saddle horse foot.