I'm also going to perform this swap and I was able to procure the wheelset from BLI (but it took some doing). They aren't really keen on providing (selling or for free) parts to be used for conversions or customizations.
Exploded parts diagram for their locos is available on BLI website. It has all the part numbers. I asked BLI for one of the outer wheelsets w/o traction tire. The confusion is that the diagram itemizes all the parts that are part of the wheelset . I asked for a wheelset consisting of 87, 88, 91, 92, 93, 94, 2 x 95.
But the original center axle also has extra washers/spacers on it (not shown on the diagram), so the wheels will need to be pulled off the axles, washers removed from the flangeless driver and installed on the flanges driver's axle.
There is a lengthy thread about this loco and there
@bbussey provided some info about this swap.