" master has two bleeder screws " Now that is an old style original Master Cylinder. I miss that kind with the bleeders right there so you can bench bleed without the bench. They are very hard to find anymore. I think the best bleed method is just having an intelligent helper work the pedal while you bleed. Unfortunately those are getting scarce too. PS- I have a 15 horse Johnson I used on a 1969 Lund. Sold the boat- kept the Johnson.