I have the moldings off my 69, so I can shoot you some pics for location of the clips and how they mount. I won't be able to post them, but I can email them would be Friday, as I am going to be home tomorrow).
As far as installation, I assume what you mean is the windshield itself? I put a new one in the 68, but being a vert that was rusty underneath, the windshield frame was tweaked just enough to cause trouble. I got the original style seal from Ricks, stuck it to the frame opening, and found that the driver side top had a 1/4" gap. So, I taped it down good and called it a night. This was NOT my first windshield install...
When I came out in the morning, I had a nice crack across that corner. Could have been a bad windshield, over-aggressive taping, temp change, whatever...
Anyway, I ended up using one of those come-to-you install vendors (Safelite), and let them urethane it in. Urethane works much better because the frame doesn't have to be perfect, but it's not original. Plus, if you have someone else install it, at least you won't be buying it more than once.
I am pretty sure you cannot "overfill" the urethane to the point where the moldings don't go back on.
Just my experience with vert windshields. Like I said, I can send pics (or get off my lazy butt and get set up with Photobucket) if you tell me exactly what you need to see.
69 'vert project big block/TKO 600 RR
68 'vert driver RS clone -- gone!