The oil sender unit will likely be the problem. The type that reals pressure for GTS dash has a bulbous head on it approx. 3cm diameter by about 3cm tall, with the little tab that the wire attaches to on top. The one that just operates a warning light (and reads max pressure when connected to GTS dash) is similar to just a bolt that screws in with the tab on top.

Never heard of an electric choke on Rochester, what model did they come out?