Trouble mounting body

[SGR]

Thanks everyone for the tips and info.

Here is what I have confirmed:
The cowl bar is mounted I the factory holes.
The firewall is pushed against the front of the frame outrigger (results in about 1/4" gap to the cowl bar at the bottom.
The firewall has approx. 1/2" gap to the cowl bar at the top (should this gap be zero?)
The body is sitting on the top of the cowl bar (so I do not think that it is hung up on firewall, although I do think the firewall is positioning the body to far forward).
I temporarily placed the door strikers on the rear frame and there is approx. 3/4" gap to the door jam. (Confirming my suspicion that the body is too far forward).

2 questions for everyone...
1) will it hurt anything to unbolt the firewall from the frame in order to allow it to 'float' while I reposition the body? Once I get the body position fixed, I can resecure the firewall to the frame as necessary.

2) can anyone tell me the correct location of the holes in the body where the rear spring adjusters pass through? They were cut into my body by a previous owner, have a very jagged edge, and are currently adding to the limitations of adjusting the body position. I am planning on opening up the size of the holes in order to allow for some body movement, but I want to get them roughly in the right spot.

Again, thanks for all of the help. Sorry for the long post...