Javoli, you have a hell of a car on your hands, both in a quality car, but also as in a maintenance nightmare. Don't mean to put it that way, but until you find out some information about the engine, fixing things on this car is going to be a challenge. So, I am sure right now you are wondering what you got yourself into. Don't fret quite yet. There are some easy answers, but it will take some research on your part.

First, as for a shop manual, I would first go to your local autoparts store and see if they sell a Haynes manual for your car. Haynes makes one for your car. It will run you about $15-20 USD. Worst case, you can go to Amazon.com and order the same manual through them for $23 USD. This will give you a lot of the "how-to's" for the car. But, this may or may not tell you the how to's on the motor though.

For the motor. Somewhere on the engine is a small plate with some numbers and/or letters stamped on it. Most likely it is between the cylinders (normally near the back of the engine) for the V-type motors. For the inline motors, they tend to be located on the engine, between the middle cylinders, on the left hand side (as viewed from the driver's seat). It may help in your search if you know what size motor you are dealing with and what brand motor it is. I would assume that it is a Jaguar motor, but I can't be 100% sure of that since you don't say yes or no on that topic. Find the engine number and then you can look it up on the internet (do a Google.com search on "engine number XXXXXXXX" where XXXXXXX is the number found on the engine). Next to this number is also normally the build date of the motor. This may be helpful too for year to year differences.

Front windows/sunroof: you know the car, your local autoparts store should be able to get you new seals. Worst case, start looking over the internet. There is a member here (Ken@britishparts.com) that can get you the parts you need to. I have used him and he will make sure you get exactly what you need. Also has some of the best prices too. Replacing the rubber seals is pretty easy normally.

As for the engine mount, once you know the motor, that will help you find the proper engine mount that you will need. It may be the mount for the 86 XJ6, may be the mount for the engine. Hard to say. You may get lucky and after crawling under the car, be able to locate some numbers on the motor mount itself. If you want to verify the motor mount is bad, it is a fairly simple test. Open the hood, start the car, put it into D (Drive) and with your foot firmly on the brake, give the car a little bit of gas. You are going to want to watch the motor. You should see the motor twist a little bit and that is it. If so, the motor mount that is most likely to fail is good. If you swear the motor is jumping out of the engine bay, then you have a bad motor mount. It doesn't take a lot of stepping on the gas pedal to do this check.

As for the stalling issue: if you know it is a bad fuel pump, I would say to replace it. Normally the pumps aren't too bad and replacing one isn't all that difficult. The Haynes manual will give you more step by step instructions on how to access the fuel pump and may even give you some checks to prove the fuel pump is starting to go.

Since you are just getting the car, I normally replace all of the standard maintenance fluids in the car just so I know how old they are. So, I would at a minimum do an oil change and flush the radiator. The other fluids I would do a level check to 1) make sure you have enough, and 2) verify that the fluid looks good and may not be in need of changing. I would also look at the engine and see if there are any signs of leaks. From the sounds of it, you probably won't find any, but leaks are normally a sign of problems to come in the future. If the car is carbureted, I would also do a tune up on the carb just to make sure things are in tip top shape. That may fix your stalling issue. I would also say to atleast pull 1 spark plug to see how they are. With 26,000 miles on the current motor, if standard plugs were used, they will be about due for replacement. If say double platinum plugs were installed, then they will show very little wear and can be used for a lot longer. Beyond that, a lot of what you need to do is to do a once over of the car to see if there is anything obvious. May want to also do a brake pad check. Again it is more just to see where the car is sitting so you have an idea of how long you may have until it may need brakes.

Hopefully this gives you a starting point. I'm sure some others will come in and give you a few other thigns to check.