You are right there should be two bolts, one either side, that hold down the front of the hardtop to the windscreen frame. The threads are in the hardtop header rail not the screen frame.
The original bolts are dome headed black 1/2" A/F hex and screw UP through the windscreen surround into the hardtop header rail. (a ratchet ring spanner is ideal to undo them) They are positioned about 6" - 7 " from the inside of the screen frame, in the lower (horizontal) face of the upper screen frame surround. Sit in the seat, move the sun visor to the side and you should be looking straight at one.
Get that roof off and enjoy the sun.
Hope this helps.
Cheers
Peter W