Diesels don't have plugs, they have Glow Plugs, and they will not light unless you hit the glow plug button. DO NOT shoot oil into the cylinders. You can hydro-lock the motor and bend the con rods.
If you replace the fuel filter, you must fill it to the top with fuel, spilling over. Then, you still might have to bleed the injectors to get it to start.
If the hoses appear dry rotted, replace them.
Diesels generally don't need tune ups. Just routine maintenance. Change filters, change oil, clean air cleaner, make sure the fuel is clean and algae free. Replace the alternator belt, make sure there is no corrosion or leaks.
Diesels are a lot less picky than gas engines. They need clean fuel and air, and cooling water.
What model engine do you have, how about some pics of the engine and the control and gauge panels? This might narrow down what engine you have.
If you have a distributor cap, you have an Atomic 4 gasser.
If not, more than likely a Universal, Westerbeke, or Renault diesel.
Oh, and CONGRATS on the 27!
PICS PICS PICS!!!