Fly,
Personally, I think your headed in the right direction given your situation. Most of us have limited choices since we are somewhat bound by existing engine/ZF components.
However, your going to have to do some careful research. In particular the distance from the driveshaft to the water pump/crank pully to make sure it will fit without using the #1 spark plug as an arm rest. DOHC nodular motors are a tight fit ( See photos of ZONKEY http://pantera.infopop.cc/eve/forums/a/tpc/f/8250045562/m/9390056393about half way down the page.
Perhaps you could get the required information from someone who knows the new Ford GT VERY well.
Ron
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.