Brett, lowering the value of R-1 in the circuit makes the transistor fire a little harder keeping a constand rate of trigger on it for the oscillations in that part of the circuit.. Going higher in resistance till it stops functioning and then lowering it till it's consistant by using a variable resistor is how I find the sweet spot!

Using a Li-Po 2 cell pack would probably be an ideal setup.. just be aware of the heating it may cause..if it's not excessive, you have a reliable circuit.
Give it a try..shouldn't be too much voltage for it.

John