What year Mazda is it that youre wanting to do this on?? Personally if I were going to do a 5.0 swap I wouldnt put an offset rearend under it. Not that it really matters, but it does make things a little tighter to work with rather than a centered differential. I seen a truck just yesterday at a small Ford show that had a shortened 9" rearend under it with a 351 (5.4). It was bada$$ to say the least, but a lot of time and money went into it. Dynos at 727 to the rear tires, but there isnt enough weight to hook up so youll wanna keep that in mind also even with a 302. Having the power is cool yet you still want your wife in a safe ride.