The GAMA format manual for the C-150M book describes a maximum performance take-off as lifting off, then accelerating to 60 KIAS with flaps retracted, to climb over an obstacle. Interestingly, the stated Vx is 56 KIAS. So we can deduce that the take-off distance numbers include the expectation that the technique described is used. Which makes attempting to back out the climb rate invalid.

If you are looking for an excuse to go fly, you can find the explanation of how to fly the saw-tooth climb and descent profiles in this web site's info on flight testing your homebuilt, and I think on other web sites. You can gather real world data for your spreadsheet that describes the individual airplane that you fly in your typical load configuration. A good learning exercise.

Best of luck,

Wes