Yeah. Be there, done that.
First thing -- make sure that your subframe is aligned. Use the dowel locating holes then double check to make sure it's square.
Next -- Move your jack stands toward the front of the subframe. If you have an old engine block and some iron heads, install them to add weight to the front end. I've heard that the door/alignment can change is you add the install the motor later.
Install the fender without the radiator support and use shims to gap the door/fender gap. Don't install the bolt on the firewall. Just the upper bolt, lower rear bolts, and door jamb. I found this sequence worked best for me: Bottom rear, top, bottom front, then door jamb. Install all four of the bolts very loosely and then shim and tighten.
Use a straight edge to make sure that the bottom of the fender and the rocker panels line up. This also pulls the gap closer.
Once you're satisfied that the gap is as even as possible, make sure the rear bolts are tight then install the radiator support.
You mentioned that the top of the fender is up against the A pillar. That was similar to my fenders. Once I had the rear of the fenders bolted in place, I use a crow bar to gently bend (or lift) that area up and away. Once you install the cowl, you may need to lift the inside edge the same way to match the top of the cowl.
To make the gap perfect, you may need to add filler rod to the leading edge of the doors. It's not as hard as it sounds, just weld slowly to prevent warping and grind slowly until you get a consistent gap.
Once you're satisfied, mark or bag all you shims so you know EXACTLY where each on belongs (assuming that you'll be removing the fenders to paint).
I encourage you to find a sequence that works best for you and write it down. That way, if you disassemble the front sheet metal for an extended period of time, you'll know exactly how to put it back. If you use a different sequence, chances are the gap will turn out differently. (trust me
)
I hope this helps,