By the sound of it you've got a faulty engine for it? in which case there should be some markings on the engine that will give away which type it is.
The fuel spitting out the bottom will probably just be a badly sealed crank cover, on the ones I've worked on it's just a round plate on the bottom of the engine that was help on by 4 allen srews, I'd just remove that and make sure the faces are clean and refit it with a smear of gasket compand.
As for the car, what have you got on it? if you have the clutch still on it then just measure in input shaft for the clutch and get an engine that matches... if it's not the correct engine you may have to modify the mounting point, but that shouldn't be a big job.