Leo, what period are you looking for?
Those cars were built in 1879/1880 and what you'll really need to find is an accident rollover image--and I don't know personally of one that exists from the early South Park. Some of these cars survived to the C&S but with modifications.
Do you have Ron Rudnick's Denver, South Park & Pacific and his UPD&G/DL&G Modeling Guides? He provides drawings in the first but because of the lack of material from the period he has had to reverse engineer a logical framing. Brakes are a bit of a mystery, the South Park moved to Eames vacuum brakes in that period, then over to Westinghouse, which took a period of several years to complete. Company drawings of these cars don't exist for that period, at least I've not seen them. Some photos from the side will expose at least cylinder and maybe rodding.
Wish I could offer more, the South Park period is a tricky one for freight car underbody specifics.
Dave Eggleston
Seattle, WA