[Ron Ramirez]

Would I have to A) Change the output transformer to one that will be able to drive a 6 ohm PM?

Yes.

B) Replace the field coil with a 3.2 K resistor? If so what wattage?

Yes. The formula P = I squared * R will find your total wattage. In this case, we know from the speakers.zip file that the original speaker was rated at 40 mA (0.04 A) of current and has a DC resistance of 3200 ohms. So,

(0.04 * 0.04) * 3200 = 5.12

You'll want to double that for safety, so a minimum 10 watt resistor is indicated to replace the field coil. Personally, I would go with 25 watts as that resistor is going to run very hot, but that's your call.

C) Increase the 2nd Electro cap from 6uf to 12 uf?

10 uF is probably enough, but you can go with 12 if you wish - and if you can find one. It's easy to find 8 and 10 uF capacitors, but not so easy to find 12 uF.

For both input and output electrolytics, I would replace with film for longevity.

D) Do I have to do anything with the filter choke?    am I on the right track here ?

No, you leave the filter choke alone and leave it in the circuit.