My zoo had a 350 in it when i got it and the firewall was just beat back a little for the distributor. They cut the crap out of the core support to fit a radiator in there. I think if they had used an electric fan they could have kept the core support stock.
I'm now running a s-10 front clip with a 350 and i had to move my firewall back three inches. The distributor is under the bottom of the windsheild.
I don't have a picture of the old crap but here's the new setup.
my boy is doing one right now, doored and doing a small block ford motor, so the distributor is in the front. he's doing a full sheetmetal firewall though