The original motor had been wired for 220V/440V (parallel/series-Y) and had 4 poles. I did separate the wires to experiment with Delta, but I didn't stick with that for long. I think I had an excessive gap between magnets to stator, as you can see from the crazy skew below. You can probably do better on the fabrication work than I did.

I tried various arrangements of capacitors and discovered that certain values helped but only slightly.

I used: 50mm X 25mm X 12 mm = 15 cubic centimeters per magnet. 15 cc's X 8 magnets = 120 cc's of neodymium.

With this I logged data for a while and got this:

Series-star: 24V Cut-in at 150 RPM. Max 300 Watts, which flattened out at 700 RPM

Series-Delta: 24V Cut-in at 250 RPM. Max 350 Watts, which flattened out at 500 RPM

Later, I added the missing magnets for a total of 12, (180 cc's of neo) and got this:

Parallel-Star: 24V Cut-in at 250 RPM. Max 650 Watts, which flattened out at 500 RPM

I suppose I should have made more comparisons, but each change meant lowering the tower to re-wire or disassemble the generator, which was time consuming.

Bringing this experience to your estimate: 60mm X 10mm X 5 mm = 3 cubic centimeters per magnet. 3 cc's X 28 magnets = 84 cc's of neodymium. That is less than I used to start with.

Your motor is wired for high voltage but you are also running at higher voltage:

1500/359*240=1000 RPM

I expect you will need to do some re-wiring to give yourself the low-voltage parallel-winding options you need if you expect to normally run at 800 RPM.

I bought mags from KJ Magnetics last time. I don't know how their prices compare now, since I haven't done a motor conversion in several years.

This one looks like a bargain:

http://www.kjmagnetics.com/proddetail.asp?prod=SB8X04-IN&cat=11The feature on the edge may be useful for holding them down.

N42 grade are OK and lower cost. I've never been too picky about magnet grade (on advice from Hugh Piggott) and never been disappointed.