I use DAP clear 100% silicone rubber sealant, it's in a blue container and you can get it at just about any hardware store for 3 bucks. 3M makes something thats the same but then your paying a little more at a parts store.
Yup, thats the goop. I used it on the doors and the trunk on the 72 and the 73. It works great and drys clear. Just remember to lightly scuff the area for a better seal.
I would use the 3M weatherstrip adhesive, and never use silicone next to metal. When the silicone cures it releases acid fumes (can't remember the type) that will lead to deterioration and rusting of the metal.
It's acetic acid but not all silicones have it. If the uncured silicone smells like vinegar then it has it otherwise it doesn't. The automotive silicones like Permatex don't have acetic acid.
The best reason to use the 3M weather strip adhesive is it drys fast. You put coat on the gasket and on the car wait a minute and stick it in place and it's done. Silicones take hours to dry and will allow the gasket to move around and possibly wind up out of place.
We always used the 3M weatherstrip adhesive when I was working at the dealer. Works really well and a strong bond. Don't overdo the application as it will squidge out pretty good. Also, a bit of painters tape helps hold sections in place as you go.
The stuff we tended to use was the standard yellow stuff, but later on before I left the dealership we started buying it in black.