You shouldn't have to do anything with the firewall as it's almost straight up and down. As far as the distributor goes if worse comes to worse you could always go to a small diameter cap from MSD and add an external coil. http://www.msdignition.com/Products/...stributor.aspx

First time I dropped in the 302 it took me 6 months as I could only work on it when I didn't have a customers car in the shop. The current rebuild is going on 12 years of work when I have time.