squeegy200

I don't know much about the MFG cassettes but I have used the American Classic versions.

the spacers depend entirely on the spoke dish of your rear wheel. Some flanges have enough angle to clear the Campy cassettes and really don't need spacers at all. However, others with narrow flanges have to be respoked/redished to keep the chain out of the spokes and rear derailleur cage in first gear.

I probably would not recommend mixing/matching gears between to Ultegra and MFG cassette. Some of those machined ramps and pins are positioned to initiate transfer to the next adjoining gear. I don't think mixing would allow the machined ramps to line up properly.