My friend installed a V10 in a 32 Ford roadster. He did nut cut the firewall and used an original 32 hood. It is a tight squeeze but it fit. After seeing that, you would think a V10 would fall in a Slick.
Here is a link to photos of that car.
http://www.jbmicrofinish.com/everetts_v10_32.html
Have you considered buying a Super Duty with the v10 and switching a Slick body onto the chassis?