As I indicated in an earlier posting to Joel in Tucson, I likewise replaced the dash cover (two component) this summer. I didn't use any glue or adhesive, probably because I had the dash out of my Amazon and could achieve a perfect fit, even around the instument cluster by doing it "dry". I wish I'd taken some more pictures, but I can say on my replacement dash, there was extra material along the bottom. I was able to anchore the dash cover with the chrome strip (the 1960 uses bolts and screws). I then cut away the excess below the chrome strip. When I installed the actual metal dash, I was able to apply some force to ensure the front windshield screws, at the firewall, secured the dash cover. The previous dash cover had shrunk so I may have wondered what impact glue might have if this process repeated itself. Anyway, that's my experience. Check with me in another 42 years to see if I made the wrong assumptions. The image below was taken after the dash was installed, but shows the screws that hold the top to the dash/firewall. Notice the speedometer scale is in kilometers.

Regards...Cam