Hi Michael.
You will find that the 767 and 757 flight decks are very close to one another.
Off the top of my head I can only think of a couple of differences.
I am currently building a 767-300ER based on the Level-D in Stafford. I tried Peter Cos at Flight Deck Solutions about 14 months ago for 767 stuff and placed orders for his new Pro-M FMC. He then turned round 6 months later and told me he wouldnt supply it and refunded my deposit (which is fair enough, I was very angry at the time but now I can understand that he was exceptionally busy and something had to give). I do recommend you try him all the same. Times change etc and he is IMHO the best!
What I am using is 6mm MDF for my MIP as it is easy to shape. I am then using 3x 15.4" widescreen TFT monitors for the CPT EHSI/ADI, EICAS and FO EHSI/ADI. I then spent about £1000 on Flight Illusion gauges for the deck. These are excellent! I didnt want to use monitors where monitors dont exist in the real thing so these gauges allowed me to keep it a little more real. I got my FMC from Engravity which connects straight into the Level-D 767. I would not presume that the FMC would connect to their 757 they are working on. I got my MCP from command flightware in New Zealand but I think mine was the last one (and it was a 747 MCP but luckily it is a genuine option that Boeing allow so I can still claim authentisity). Check them out, they might have more. I bought 2 yokes from Dodiano here in the forums. These again are excellent. Search his username and ask him if he has more.
I am using OpenCockpits, SIOC and Lekseecon to connect the hardware to the software and it is all pretty straight forward. If you havent seen this site then it may be worth a look
http://www.simpit.de/b767dim/index.html
I think that just about covers it except to say welcome to this extreemly intersting and expensive hobby. Hope it all goes well. I also offer an invitation for you to come and visit my sim as I must live only about 40 miles from you. (I warn you that it is NOWHERE near done yet) ;)