Projector suggestions for 11'x22' screen

I am helping out with a small film festival and we have acquired use of an old vacant theater complex. It consists of two theaters, both with 11' x 22' screens. One theater has a throw of 37', the other is 46'. One of the organizers has a connection with Ron Perelman (who is the majority shareholder in Panavision, among other companies) and Panavision has agreed to donate some projectors. I am unsure what we need to ask for since, as far as I know, they don't sell digital projectors (do they?). Most of the sources will be DVD or Blu-Ray, so a cutting edge projector is probably overkill? As you can see, I don't know much about this level of D-cinema ... I'm just a regular-old consumer level home theater FP guy. What kind of lumen output do we need for these screens?

Any suggestions would be appreciated. Also, PM me if you or anybody you know would be interested in volunteering to help out with the technical side of the festival and you live in the Twin Cities, MN area.

Thanks for the advice ... so I'm assuming the HD8k would be too dim? How would the HD8K brightness compare to a traditional projector in your average cineplex? I'm also assuming the HD18K would have sufficient brightness?

I'm still not sure what Panavision's plans are for the donation. Our fundraiser has told us that they will be donating the actual projectors to the film festival (physical donation, not a rental donation). I'm still trying to get more info from them on what that actually means. If it were some random company, I'd be concerned that they wanted to donate a couple of used boardroom projectors ... but you'd think that Panavision would understand the significant requirements of a theater projector.