Anybody have experience with really old Diesels?

Well, we got it running! It just needs a thorough tune-up (oil+filter, coolant flush, air filter conversion, injection timing) and cleaning (injectors, etc.). I'm now wondering if there are any ways to increase the power of this engine, as it seems like it might be able to handle more. It is unbelievable slow; so slow that I think it would be dangerous to drive on modern streets (a factory-rated output of 40 bhp and a curb weight of 2800 lbs!). I was at first thinking about a turbo, but that might get too involved and I don't want to compromise the engine's durablility (the engine isn't supposed to go over 3200 RPM!!!). I tried reading in the service manual about how to crank up the injection pump but I think I need to take apart the pump to get a good understanding of it.

Something I don't understand is that the injection pump has some sort of weird vacuum regulator thing (along with a throttle(?) valve at the opening of the intake manifold). Can this be modified somehow to increase performance?