I think the longest leeson will make is a 1055wb. I heard rumours of the curtis too, give them a ring and see what they say!
You could always upgrade your pashley to the 25GHz, only clocks in at 1030ish, but is a very nice ride!
The other option is to contact some other mtb frame builders and see what they say! (the like of Dave Yates and others, look in yellow pages or try google!)
depends on the what steel you build it out of more than anything, but a decent steel frame won't weight much more than an alu frame. And steel ride much nicer (Y)