Have you tried here
http://www.b737.org.uk/ , its what I've been using for my work on the B737 cockpit I'm working on for FS over the years.
I may have some more information on layout and some drawings at home in one of the manuals somewhere, I don't think they are too scale but look reasonably ok proportionally.
I prefer the older style cockpit but prefer the newer high bypass ratio engines, can't have it all it seems ?.
Sadly I dont have the space for a 1:1 cockpit, but it would be kind of cool, actually come to think of it there is or was a site about a bunch of guys making a 1:1 sim cockpit, I'll see if I can find the link tonight when I get home from work.
I've also got some manuals of the 100 somewhere, I think ?, I'll have to dig through my 737 reference collection to be sure though, too much to list here.
With regards to modelling with out drawings, we guess

, seriously its difficult to get access to many cockpits, though I noted that Aerosoft were actually allowed to measure up the A320 for their recent project, but generally speaking I think most people scale stuff so that it looks right and generally thats good enough for a virtual cockpit, I've also found that exact scaled stuff tends to look odd in the sim due to the POV that FS uses, most people fly with a much too wide angle camera view.
Hope that helps
Michael