Team, hopefully this isn't too silly a question, but what is the best way to lower the front of my 68 coupe? Drop spindle or lowered coils?

The "best" way is to use the spring of your choice to get the height you want ;)

The drop spindles are terrible on 1st gens. They trash the geometry and cause problems with tire/wheel fitment.
Here is some info from David Pozzi's great personal site on 1st Gen suspension - http://www.pozziracing.com/first_gen_suspension_geome.htm#Drop%20Spindles

Also try a search on this site using 'drop spindles' as the keyword(s) - you'll get hundreds of posts with information you can use.

dropped spindles are a good option on most cars, just not ours!

Let the air out of the tires..:D