worth it or no
 

I know nothing about the Mazda truck. But Im about to buy one maybe and I need some advice. I am looking at an 86 B2000 with 215K on it. 5 speed ext cab. Runs and drives ok no engine noise etc. Seems ok . Just want to know is the mileage a problem with these trucks ? The truck has a few minor issues but nothing major. Just the reliability of these engines is what I need to know about. Any help appreciated.

Need some advice please

Each manufacturer has their good and bad. You can have 2 of the very same trucks that came off the assembly line the same day and one could end up riddled with issues and spend much of it's life in the shop and the other be totally reliable.
On the other hand, you can buy an older truck like the one your looking at with lot of miles and still have lots of life left in it.
If your sell can show you a maintenance history or repair history If it was well maintained I would go for it.

If the body is good buy it.....Those trucks tended to rust away before the drivetrain went bad. I take it you live in a dry, no salt used on the roads climate.....lol

Good deal! If you plan to keep it, drive it while you save/acquire a v6 eng/trans. you can probably do this for the cost of the hard to find parts for yours plus labor and machine work.
A 4.3 GM Vortec from a truck is a drop in fit. No butchery needed, use original radiator.
Not sure about the shifter location for a standard, I used an automatic. I figured 190 horses, I could get gone quick enough!
Change to a carb, and 86 HEI distributor, or get the wiring harness and computer with the engine. I did it to lose the bot in a 90 B2600 Extended cab.