Package tray repair

I have proceeded to reinforce the package tray.I have the 3/8" holes drilled in the corners,ready for the flat steel stock.The window is out and 13 1/2" lengths of wood are in place to maintain window opening.The weight is off the corners by placing the prop at the front of the top and the bottle jack is in place.The question is how do I know when the package tray is in its proper position to cut the slot and weld the steel stock? Any help is appreciated.Paul
Dave's answer to this question is to set the window back in the frame to square the frame and jack the package tray to achieve this.

After jacking the package tray the R top corner of the window is not quite equal to the L side.A quarter inch gap on R side,no gap on left.The right corner needs to go up 1/8" which it doesn't go.I decided to change the 18 bushings on the lift assembly to see if this would help.Can anyone give me the proper procedure to do this repair? Thanks for all help I might get.I've also have a web site with additional information.It is 57thunderbirds.com and on the home page click on the retractable link to get to the web page.Paul

I'm back working on my top problems and have made some progress.I've changed the bushings and beefed up the corners and think I have a good foundation for success. I am very weak on the electical part of the restoration.I found a Ford service forum that is very helpful to me for switch ID that I'm going to post.Feel free to help me out.

yes paul i'd did many like this and propped roof up on blocks a sleightly higher front of roof , than rear a inch at most then roof jack screw adjustment leveled it off for even hit