1955 13ft step hull - placement of gas tank and battery; prop type and pitch

[kevlarbike]

Have a 1955 step hull boat that is 13ft long and the bottom extends 6 inchs past the transom with a cutout for the engine. boat is 5ft beam, 2 inch step that tapers to 1/4 inch at the chine. Step is 78 inches from the transom. Have 50 hp short shaft on the transom mounted 2inches high. There is one more mounting hole left to raise it to if need be. I have put the battery -26lbs infront of the step by 12 inches and then infront of the battery is a 12 gallon gas tank 72lbs. I weigh 130lbs and the boat weighs 350lb and engine 204 lbs. I run a 15 pitch 4 blade trophy. The boat runs 37mph but runs 6000 rpm with the engine fully raised.It will run even faster if the water is a little rough and the boat is on top of the water; I believe it plows to much and should sit higher in the water. I tried an 18 pitch 3 blade and it could not really get on plane, drove the bow down and would almost stop moving at 4000 rpm. Air lock . Both are new props. I was told the two props are very different, 15 pitch cleaver, 18 pitch chopper? I think that since this boat was designed in 1955, back then everyone put the battery and the gas tank need to be in the very back of the boat. This will raise the bow higher and then maybe the 18 pitch prop ..will work. This boat was suppose to be a very fast boat and I believe it should be faster then 37mph . Thanks for any help.

[mach1magnum]

in the picture there is to much boat in the water to be fast i would try moving the tank back or leave it empty and get a portable tank to try and see what happens or of course you could always strap on a diamond 280 like some people i know would do (albie)