I think most here on the FB are more familiar with Ford (Murray) produced 3W coupe bodies and less familiar with the Brookville 3W body. How closely does the Brookville interior construction follow the original design? Are stock regulators used in the doors and back window?
Back glass
A stock 32 3W has an interior upholstery panel below the back window covering the regulator panel. If your completed interior has this feature than you should be able to remove that panel and the regulator wood panel which would then allow you to install the back glass. Start by placing the back window (with channel attached) in the drain pan, then raise it to the closed position. Hold it there with a piece of wood. The rolled edge of the slot on the window channel should be towards the back of the car. Then install the regulator panel with the regulator installed. When installing this panel the roller at the end of the regulator arm must inserted into the window channel. It may be necessary to adjust the arm up or down to make the connection. Pull the piece of wood holding the window up, attach the window regulator panel to the uprights. Check function. Adjust as necessary.
Door glass
Start by placing the glass (lengthwise vertical) with channel attached in the door, then rotate and raise it to the closed position. Hold it there with a coat hanger. The rolled edge of the slot on the window channel should be towards the outside of the car. Install the regulator. Raise the regulator arms up to meet the window channel, insert the rollers and turn the window crank to engage the rollers in the channel. Remove the coat hanger. Check function. Adjust as necessary. Good Luck.