"i know that the grater the frequency the more volts will be generated."
Life is not that simple. This is true if you increase frequency by raising speed.
For a given speed and size of machine it is far less simple. If you double the number of poles to increase frequency you have to use smaller magnets to get them in.
V is proportional to flux per pole, frequency and number of turns. As you raise frequency you lower the flux per pole.
If you want the original winding you are stuck with one frequency at a given speed. If you want to rewind you can likely increase the number of poles as long as the number of slots permit.
Smaller poles will likely reduce your dead end windings and you will need less iron for the same volume of magnet.
Volts are determined by the number of turns per phase, current is determined by winding resistance(and reactance for motor conversions).
For a 36 slot core I would try to avoid 2 pole ( too much dead wire and no room for flux path below magnets. 4 pole is reasonable but awkward without curved magnets.
6 or 12 pole most likely would be the best compromise.
Once you have decided on your number of poles then you will gain a little bit by filling the rotor with magnets but a small gain for a lot of extra magnet. Normally for a 3 phase winding the pole arc should be 2/3 of a pole pitch to use the windings and magnets best. That means gaps between magnets about 1/2 magnet width.
With ceramic magnets the more you jam in the better, you still will only have low flux. Excess neo will most likely add mainly cog and iron loss with little gain in output.
Flux
