I see you finally arrived to the point you need weight and HP into the formula, as I mentioned back on Aug 1.
All this charts and data is getting off topic of the OP. This extra charts and math is too much for the OP intent.
The OP has 2 donor boats and he wants to use the parts on hand, the 1:1 driveline is his best choice, we do not need all the charts and math to come to that conclusion.
Empirical data is conclusive enough:
1. Dave Lott had a 1.2 gear in Riviera, and he ran out of prop size, he was forced into custom prop size to hold engine RPM
2. Butch has a 1.2 gear, but he has a 25' boat, another foot of beam, and 1,000lbs weight over the OP.
3. All the other V8 guys at Gathering are 1:1 and use a 13x13 or 14x14 prop just fine and dandy
4. The chart you posted about hang the largest prop diameter possible, is not totally true. True for trawlers yes, but not planing hulls.
5. Read Gerr's book again, you're missing a lot
6. Planing hulls accept smaller diameter props, but trawlers accept largest diameter
7. 1.5:1 gear and 14x18 prop on a little hull like OP would have a tremendous prop walk in reverse, his rudder will be totally useless in reverse
8. 1.5:1 gear in a small hull like OP and he will likely run out of prop as Dave did in item #1 above (ie expensive custom)
9. I have personally run prop sizes from 14x17, 15x15, 16x16, 16x18, 17x14 4blade, the large diameter is not needed in calm water on plane.
10. The OP is not taking his BB offshore in 6' following seas, he doesnt need that kind of torque from a reduction gear
11. The OP has a 1:1 with 1" shaft, 13 or 14" prop already on hand, empirical data will show that to work fine and dandy
12. The 15x18 1 1/8" prop is not as easily exchanged for sizing, as a 14x13 1" will be. he can find these on Ebay.