The upgrade should work perfectly as the 486slc was just a modified 386sx (with its 16mb limitation) who was optimised and faster but don't expect to much of this product it is not comparable to any 486 (SX or DX) but it is the fastest PC card made for the amiga.
Just one other thing: as far as I can remember 486slc2 could run faster than 50mhz (80mhz was the maximum) as far as you can raise bus frequency ...
