Brabdy Smythe writes of adding gutter to poptop to fasted roof mounted
stuff.  I added large eyebolts (1') with very large fender washers all
around the poptop of my 78 100,000 mi ago- three on each side, two in rear-
and found therm indispensable to mount roof racks, carry plywood, tie
biycles flat up there, large inner tubes for shore.  Make sure to use SHORT
eyebolts (I cut and ground them down so inside can't poke fabric) , and use
silicone under washers and around bolts and over exposed threads.

I did this on my 71 also; remember adding some to frame below also so rope
could be tied down there to take stress off roof when carrying large
plkywood sheets.        MB in NJ