narrow gauge passenger cars

I have a few questions about 3ft gauge passenger cars. I like to draft railroad equipment (mostly narrow gauge) and I design alot of stuff myself. One car that I designed is a baggage/mail/passenger car. The car is about 8 ft wide, around 11ft tall, the body is 40ft long and is an overall 46ft long from platform to platform. Do these measurements sound about right and are they close to cars used by the D&RG? I want to make sure that the measurements are about right before I go ahead and build the G gauge model of it out of wood. Also would anyone out there have pictures of the interior of a D&RG passenger car and the mail room of a mail car? Any help would be great.
-Eric