Nice motors at a very nice price. They are rated a 3A per phase so you will be able to get significant mechanical power from them.
8-wire motors are universal motors meaning they can be connected bipolar series, bipolar parallel and unipolar. I looked at their sparse datasheet so I'm guessing the ratings are:
Bipolar parallel. 3A per phase, 1.2mH inductance. If you use the G540, 35VDC is the maximum power supply voltage for this connection.
Bipolar series. 1.5A per phase, 4.8mH inductance. 70VDC will get you exactly the same performance as 3A at 35VDC parallel. Can't use the G540 there because it can't go over 50VDC.
Unipolar. 2.1A per phase. 1.2mH inductance. 35VDC max supply voltage.
Bipolar parallel will get you the best performance using a reasonable supply voltage (24VAC secondary transformer gives 34VDC after rectification).