Try a dock start, should be easy. Weight in the front of the boat should help as well as someone else already mentioned. Move your fuel tank(s) as far forward as the hose will allow.
As far as the motor, it is plenty for skiing around on a pair of skis on a light boat like that. What prop do you have? Lower pitch will help the hole shot but lower top speed. You should have it set in the forward notch trimmed all the way in for better hole shots. On engine height, the cavitation plate should be even with the bottom of the boat. Does is run ok? If not the coils crack a lot on the older OMC's, spark should be able to jump a 1/2" air gap. (don't just pull a plug to see if it jumps to the electrode, that is only .030" and the stator plate is a little farther than that in most places from the coil so spark will take the path of least resistance and jump .030 first, but remember it takes a lot more to jump under compression. The '57 35hp had the old pressurized fuel tanks. Make sure the tank is building up pressure, easy to tell by taking the cap off and hearing the pressurized air come off. Another thing to check on that engine is carb adjustment. That engine has adjustable high and low speed jets. To adjust idle, loosen the packing nut enough so the jet can turn, turn it all the way in until it barely hits the seat (not too tight or you will mess up the tip). Then back off 2 turns. With the engine idling gradually screw in until the you start getting some coughs, then back out until it stops coughing. For the high speed jet (the one on the bottom), repeat the process and start with it two turns out. With someone else driving the boat wide open in gear gradually screw in until speed starts to fall off, then back out slightly until you are at the fastest it will go. Tighten both packing nuts and you are good to go. Also there is a rubber roller that follows a cam on the stator plate which synchronizes the carb and spark. the throttle butterfly should just start to move when the roller passes the mark on the cam. To adjust loosen the two screws on the bottom of the cam.