Welcome to Stangnet brother!
What're you thinking for a V8? A 289? Or something a little more wild? I've seen a coyote dropped in a couple classic mustangs too.
We have a classic subforum that you should start a new thread in. Posts pictures of what you got and tell about what you want to do. You'll find lots of help through pretty much anything you want to do there.
I paint cars for a living, so if you need any help just post my screen name with an @ sign before it and I'll get an alert. I'll try to help you out the best I can over the Internet.
Good to have you with us!