Sante hubs came in both freewheel and cassette versions. However, they are readily distinguishable. The cassette version has a hub shell center section that noticeably bulges, starting about 1.5cm from the drive side flange. Also, the hubs may be marked with part numbers in the center of the shell. The cassette version is FH-5000 while the freewheel version is HB-5000.
Even if you have the freewheel version, there is another precaution. The Sante rear derailleur came in two cage lengths. The RD-5000 is only rated for a 24T large cog, while the RD-5000-LS is rated for a 28T maximum cog. Again, the part numbers should be marked, on the back of the derailleur parallelogram. Diven the original cog range, I suspect you may have the shorter cage version.