I've spent the recent couple of weeks working on a small program to make converting rF1 engines over to the rF2 throttle model an easy task. At this stage, I'd say you can put an rF1 engine in the program and get an rF2 engine out in less than a minute. And the engine you get out of it is ready to drive immediately in rF2! (Though you may still need to pack it away in a .mas file, if that's how you're organizing it).
Engine and fuel parameters are typed in which are used in the conversion. Bore, Stroke and number of cylinders is easily looked up on the internet for most cars, or reasonably estimated by looking at technical regulations. Fuel density and air/fuel ratio varies with different fuels, but the main parameter to look at is Max flow. This limits how much air goes through the engine. This neatly works as an air restrictor too, as when you pull this back, you see the torque drop at high RPMs while remaining the same at low RPMs, just as you'd expect.
It shouldn't be long before this sees the light of day either. :)