For the a/c box, there are three bolts that I'm sure about, that go through the firewall to the heater core box part. There's two on the bottom and one up top. If you loosen both nuts on each double-ended stud, you might have enough play to figure out which end of the stud to take out - heater side or condenser side (I forgot which is easier). You'll need to pull off the fan speed resistor module, cables, and heater hoses, too, and anything else like that.
I don't know how much room that will give you... It might be easier to pivot the engine up on the driver's side motor mount. Otherwise you may have to discharge and recharge the ac refrigerant, and disconnect the hoses. If you do the pivot thing, all three pass. side bolts have to come out, and one of the driver's side bolts, with the last one loosened a little to allow a swing/pivot without tearing the rubber of the mount.
Quick tip of the day: the two rearmost head bolts might need to be held halfway out, as they won't be easy to pull out all the way while in the car. Use rubber bands, or some such, to hold them up enough to clear the block surface without scratching against it.
Just a note on the gasket failure...these gaskets do not fail often. Make sure you get the head magnafluxed, and/or at least pressure- and warp-checked before putting it back on.
'95 P71, 5xx,xxx miles, Rebuilt tranny, 2.73. Lives as a cab, and will die as a cab. (Died-FrontEnder)
'96 P71, 640,xxx on original drivetrain. (Now parts car - T-bone & roll)(You should see the roof - A,B & C-pillars chopped on driver side)
New to list: '96 MGM (Nice! @ 35x,xxx), '97 CV P71, '98 CV P71, '00 CV P71, 01 P71 (2 of 'em) '03 CV P71 (Nice so far) (All Ford Zinc Yellow w/Black decals & trim) And the list is growing...........
Taxicab mechanic: I HATE DRIVERS!