have you discovered http://www.ford-y-block.com/technical.htm John Mumert has a lot of good information on there about parts and what to look for and where to look for numbers etc.

The wider mounts are probably the truck/t-bird mounts which is what you need for a f100.

the number on the timing cover is probably a part number. most ford parts have them somwhere.

Research is a good place to start with a project.  it helps ask the right questions. I literally have small libaries on some of my machines, read cover to cover. It can be the most fun of the project. just don't sit next to me at diner parties. 

Cheers

Warren