Mack cab question

[Mustang46555]

Seeing Lmackattack's fleet at Indy this year has motivated me to dig out my Masolite block truck and give it a cosmetic make over as well as get the boom operational. I had lost interest in the project and shelved it because no matter how I tried, the King Hauler cab just wasn't right on ole 773. She was a 1973 DM600 and needed to at least look like a Mack.
The Shapeways cabs aren't DM600's but I can live with an R model cab. Problem is, the more I go through Shapeways web site the more confused I get. I need the correct combination of cab and hood that is the same length as a day cab King Hauler since the bed, headboard and boom are already mounted.
Any advise would be greatly appreciated.