Should I build plinths or screw spikes into cabinet?

I've got a great old pair of B&W DM640 floor standers, but I don't have the plinth and spike kit that were sold as an option back in the '90s.  Since I have been unable to track down a kit online or directly through B&W I am planning on building my own.

The speakers themselves were built without any isolation system on the base of the cabinet, and were set on top of adjustable "lugs" which were incorporated into the top of the optional wooden plinths.  Each plinth had four basic spikes mounted at the corners.  This sounds easy enough to replicate.

Does it make more sense to simply drill into the base of the cabinet and mount the spikes directly?  The tweeters are nearly at ear level, so I don't need to lift them much.  I am a little hesitant to make any permanent alteration to the speakers, however.  Any opinions or alternatives are welcomed!