Without suitable measuring equipment you efforts to improve such a simple circuit are likely to be frustrating at best.
At 150MHz, the stray capacitance and inductance in the component leads and components will be a significant proportion of the effective inductance and capacitance of the resonant circuit.
Looking at your website, at one point you comment that you are using antennas which are 5 inches long, this is likely the biggest loss of efficiency in the system.
Also in the website there is a schematic showing a transmitter with a 12 inch antenna and a 12 inch counterpoise, this will be much better, but 12 inches is still an bit short for 150MHz.
If you could make the antenna and counterpoise 18 inches long, that would be about optimum for 150MHz. But I guess that may be a bit big for the turtle!
Make the antenna as long as possible, and use a counterpoise.
Adding a counterpoise to a transmitter with a short 5inch antenna will give an improvement, probably more than fiddling with L and C values.
What do the turtles think about this:
Alien Abduction !
JimB