My truck is a 55 1st series with the single piece curved windshield, Richie, so I don't know how close the following info will be to your situation.
The front section goes in first with the headliner cardboard tucked under the windshield rubber gasket. You might have better luck by putting the support bow on the front headliner piece before installing it. Then the back portion is fitted into the bow and the trim piece screws into place over it.
Another tip to make the process easier is to spray a 50/50 mixture of water and household ammonia on the backs of the headliner pieces to make them temporarily more flexible. Just mist it, don't soak it soggy.
Can't tell you how to locate your mirror and visor mounting holes as I haven't done that successfully yet. I have my winshield out for replacement right now and my headliner is out as well. I will be making another run at a new headliner and insulation when I get the new windshield back in.
Here's a link to a log entry on my website where I had my first dealings with the headliner that describes the above in more gory detail.
Odds n Ends Good Luck!