Waistcoat Length

[Mickey]

I was lucky enough to come across a nice suit coat with a 5 button waistcoat yesterday and the coat was just begging me to cut down it down to kilt length, but what about the waistcoat? Would it be fine as is, or do these normally have to be modified also? Where should the bottom points fall on a kilt, assuming that it shouldn't be cut flat along the bottom?

Any general rules of thumb to follow here?