by 'hardware'.. I assume you mean the washer/rubber/nuts? but the studs ARE installed in the spoiler from the factory?
Are you talking about a hunk of 1/4"-20 threaded rod, or the original double ended studs with a lag thread on one end, and 1/4-20 on the other with the integral step between them. The ones I've seen have threaded rod only.
I don't really know what was installed in the '68 spoilers, but I'm familiar with what is in my '69 .. which is a double ended stud, with a wide flat flange in the middle (which serves as a stop when the stud is screwed into the fiberglass spoiler, and serves to prevent the fiberglass from being busted out by too much torque.). The following photos are from my factory original rear spoiler studs and retainers (late 09C car).
1) first photo shows both a rear (short), and front (long) stud as used on the rear spoiler (there are 4 of each, and the long ones *may* come be installed in two differing lengths, with the longer ones used on the center two locations).
2) Second photo shows the two different retainers (nuts with encapsulated washers). The nut with the wider washer also included a 'rubber washer' which served as a seal to prevent water from entering the trunk around the stud - the rear most studs were located behind the trunk area).
3) Third photo is of one of the longer studs after removal from a spoiler. It isn't very visible in this photo, but this stud has a wide thin flange 'stop' between the two threaded sections).