I have a 1987 Mazda b2000 with a 2.0 engine and it's gone what year and cars and other engines will interchange in the 1987 Mazda truck

For a quick and easy change over , get a good engine from the wreckers or from an engine reconditioning retailer same as the one that is in it
If you want to up grade get a bigger mazda engine 2.2ltr and check the box bolt hole pattern
if they are the same , change the engine --if different replace engine and box as an assembly