I might worry about the machine screws working or just pulling out under high load if they are just tapped into the aluminum. Have you seen the mast hounds that are available? Rigging Only in Fairhaven Mass. has them in their on-line catalogue:
Rigging Only - External Mast Hound for 5.2x8 mast section 1/2" pins
It may be wise to weld on a strap around the mast so that the machine screws have shear load instead of an angular load.
Have a look at the picture once more
The machine screw is not
tapped into the aluminum.
The tang is made in two parts. You make a slot in he mast and thread the two halves in so the flanges sit inside
The purpose of the screws is to prevent the tang from falling into the mast.
A neater solution than the mast hounds.