ClassicCar

As I was talking with my grandpa this weekend he mentioned that he would be interested in selling some of his old farm equipment. One of the pieces he is thinking about sending down the road is a portable welder made from a 1927 Whippet. I guess the story is the Whippet was traded into the local Chevy dealer back in the 1930's, the dealer who was a tinkerer built this rig. My grandpa then bought it on his auction in the 40's or 50's.
About the Whippet, I have not looked at it for a long time but seem to remember it is a six cylinder. It has not been run for a few years but is complete, with original radiator and sheet metal (hoods). Grandpa says it was one of the sweetest running engines he has ever been around. The engine is mounted on a two wheel cart with nice wooden wheels.
I am charged with finding out approx what this rig would be worth. I am not really sure where to start, and can't seem to find a great deal of info out there on the Whippet. So if there is anyone out there who would be able to tell me approx value, or perhaps just what to look for, or just more about the Whippet I would greatly appreciate it.