My first impression is that this is a good deal. But.....

The good
-If the body damage is just dings, it should be like any other car to address. The body is steel, so a decent body shop should have no trouble.
-Fiberglass can be mended.
-Parts are available. Only a few things are no longer available, but those situations have been rare for me. Part prices vary. Many components are off the shelf items and sell for average cost. Jalpa specific parts made by Lamborghini are really expensive.
-The Jalpa seems to be ranging in price from 30,000 to around 45,000. The low end needing a little work, the high end being a well sorted excellent car. (Correct me guys if this has changed)
In a bad situation, an engine rebuild would run around 15,000. Most likely the brake booster and master cylinder will need to be rebuilt. Based on the information provided, you could sort it all out and just about break even in value. IF IT GOES WELL.

The Bad
-It sounds like that car has been sitting, and during at least some of its life, negelected.
-Seals and hoses are most likely bad. (Check the fuel and oil return lines if you try to start it. Fire prone car.)
-Check out the engine cooling system.
-Check the motor mounts.
-Check the break system. Brake fluid has probably broken down and will require a rebuild.
-Check the water pump.
-Switching to stainless valves is recommended.
-Suspension should be checked out.
-Carburetors will probably need rebuilds.

There is probably more, but this is the big stuff.This, plus more, is what I have been through. It is all do-able. Parts are available. But no matter what the situation is, the car is going to need some of the stuff I mentioned and it is going to cost money. Any 23 year old car with a history like this is going to need work.

I can give you a blow by blow of my Jalpa experience if you like. What I listed above should give you a general idea. My specific experience can give you a lot specifics about what ownership of an unsorted Jalpa can be like. NOT that it is bad! I love my car! But it is not trouble free or cheap.