I have a standard modern 1334 that the morse taper is a bit rough.
Do you have a picture showing what you mean by “rough”?
You might be able to knock down the high spots by using a MT3 cleaner wrapped in very fine emery cloth or fine grit wet/dry sandpaper using WD40 as a lubricant. Any dings below the surface are not going to matter.
Here is a link to a supplier (not affiliated)
https://www.traverscanada.com/morse-taper-spindle-cleaners/p/370897/
I have even used a piece of wood as a holder for the sand paper to clean out dings in the taper. Works well.
You can blue up a known good male MT3 to monitor progress of you work.