44's under a Ranger, it can be done, but it is going to take a bit of work. As for the Ford 8.8 holding up, the larger tire size is like putting a long breaker bar on your axle shaft, horse power is not needed to break stuff. If you swapped in a 31 spline Ford 8.8 with chromoly shafts, you could probably get away with 40's, but that is a little bit of a stretch. As for the D44 holding up in front, it will hold up until you put it into 4WD.
I am actually planning on building up my Mazda with the target tire size being around 40's. The front axle needs to be pushed forward, as does the rear axle to maintain a reasonable turning radius. Steering should be either hydro assist (recommended for street vehicles) or full hydro (if you want to put a bunch of money into it). Gearing, go as deep as you can, would recommend running a doubler. As far as suspension, that is kinda up to you, I just recommend keeping it as low as possible for stability.
I have been pulling parts together for my rig for some time now. I have a completely dressed 5.0, an NP435, a BW1356, an NP205, and a set of D60's. Even with all of these parts, I figure that it will still take between $20,000 to $25,000 to put my rig together the way I want it.
It can be done, just takes a bit of research/time/money/work to pull it all together.
hick