I think it might be an old SP O-50-4 fuel oil car from about 1905,those were large (12,000 gal) and both the small dome and the "fore and aft" elbow safety valves would fit. I also think it is a radial course tank
rather than insulated.-can't see any lip around the end.
As for modeling,I think I'd look at Tony Thompson's SP freight cars book vol.5,p.247 for starters.
I think these cars were written up in the trade literature when they were built also.