Cool, sounds like your all set then.
$150 is certianly a good price, its hard to give an estimate in US $, but I guess it will cost prehaps another $2,000 to complete the car.
Depends interly on how much you can do yourself, but things like painting and rust proofing the chassis will add up quickly.
I recomend haveing a really good search of the internet, there is quite a large comunity of Triumph fans online all of which will be happy to help.
As your totaly rebuilding the car I recomend building it to a later spec, A MKIII would be best, as they sorted out the rear suspension and made them a lot safer and faster.
You also might want to consider useing a later engine and g/box from say an early RWD Toyota or Nissan. As well as a Differntial from an early RWD Nissan. The Triumph engine is very strong, but not terriably powerful by todays standards, while the G/box and diff are unforunatly notoriously weak.
The Toyota K series is a perfect engine, or if you want a bit more power then a T series will do. Both come with a 4 or 5 sp gear box, and both are an easy fit into the Triumph chassis, requiring only minnor engine mount changes. The Triumph electrics will then hook up to the Toyota ignition and starter.
If you do run the standard diff then there are ways of getting them strengthened, any good diff specialist will be able to do it, and I cant recoment it enough.
Also take the time to get the chassis properly dipped and coated to prevent rust. If left unprotected it will go bad very quickly, and the extra expense will pay off by increasing the value of the car when it comes time to sell it and move on (or keep it for the grand kids

)
Anywhere, heres a few links Iv had lying around from my Triumph owning days:
Triumph Webring, which links to over 160 Triumph Sites:
http://n.webring.com/hub?sid=&ring=t...autos&id=&list
Triumph Home:
http://www.team.net/www/triumph/
Triumph Register:
http://www.vtr.org/
US Triumph Parts source:
http://www.triumphsonly.com/index.htm
Someone rebuilding a GT6 (same chassis as the Spitfire)
http://www.gt6man.freeserve.co.uk/Index-fr.html
Triumphs:
http://www.eimc.brad.ac.uk/~ijpalmer...phs/index.html