Fitting Screens together

I'm (my parents) are building a new house, and I am designing my room around an LCD Projector. I have a very long wall in my room, which is conviently going to have no furniture along it. I want to have at least a 12 foot screen projected on that wall. So I've been looking at various screens lately. I need something as big as possible, and I want a silver screen. 6' x 8' screens are quite expensive on ebay, and im my opinion not big enough.

If i got 2 70"x70" screens, removed them from their casement, and cutt off the black border, could i make a 140"x70" screen without too much of a visible seam ?

(I'll post pictures of my room when I get it done)
Silver screen!

Silver screens are the best for brightness and higher contrast on LCD projectors. Glass bead is bright but kinda washed looking as the blacks look light grey (yuk). A silver screen is a very good choice. You can join screens together. Look at the movie theatre. They are more than one peice of fabric. Plus when damaged they only replace a section not the hole thing ($). So there is a way though I dont know how. Plus you would want to use silver thread to join them or put them on a backing of some type and use glue on the backside which prob would be best as to hide the seam. Anyone else have ideas?

p.s. you could try searching for screen repair stuff. That might find the mending materiels and etc. I know they sell paint to refinish them too.