My friend, what happened to the original engine ? Is the Mazda engine's weight - power ratio compatible ??
I have known Sportage to house Hilux engine, mileage was pretty fine and so was the performance.
What you need to do is have a compression test done and see how good your engine is. Mazda 2200 is from the Mazda van or the double cabin they have ? Its more of a torque-y engine than speedy one.
My cousin has had the 2 versions of the sportages & has taken the Grand from Karachi all the way to Naran loaded with supplies after the Oct 05 earthquake. Went and came back fine.
Also you need to ensure that the tires are not too big, that will have an impact on ride quality, mileage and pick ........ in the long run your suspension & steering box.
Post a pic.