Help with Solas install

[nola mike]

Just got a Solas Amita 3 to replace the OE on my merc 25 2 stroke. The original, according to the manual, had a forward and rear thrust washer (though both seem fused to the hub). Then theres a plastic-y nut with a flange that holds it all on. The new prop has a splined brass outer fitting, and came with a tabbed thrust washer. The old nut won't sit in the recess because of the flange. I assume that I don't need to reuse the merc thrust washers? And that I'll need a new nut that will fit snugly in the new thrust washer? In the meantime, I'm going to see if I can reverse the nut so that the flange is towards the rear. Or maybe I'll try to cut/grind the flange down--I won't be able to get the correct nut this weekend...
Oh, the flange end of the nut fits nicely inside of the outer brass fitting, but then I can't use the tabbed washer with it.