Not to be too much of a naysayer but this probably isn't gonna work out and if it does it probably won't come out nice without a TON of fab work thrown at the chassis to make the TTB fit into it.
Track widths are comparable enough to probably work. You're gonna have other problems though.
The Aerostar "frame" width is much wider (I can measure later if I remember) and will conflict with where the coil buckets want to be so you need to move them out or go coilover.
If you intend to build an off road Aerostar you are going to be stuck either running tiny stock-ish sized tires or having stupid amounts of lift because there is close to no space between the front tire and the driver's left foot so you'd need to modify the firewall if you wanted to be able to cycle, let alone turn, a 29" (i.e. stock size for Ranger) tire. The wider frame is also somewhat of an annoyance for the radius arms because it moves them outboard which also has the effect of limiting steering even if you do cut up the firewall. If you do choose the "stupid amounts of lift" route you'll have to address the rear because the rear because all the control arms are really short because this was only ever intended to be a street car. Making longer lower links and new mounts is a simple fab project. The upper will be a packaging nightmare because there's a gas tank in the space you would want to move it to.
I briefly considered doing a similar swap and concluded that it would be a massive PITA no matter how I did it and that tracking down a 4WD Aerostar donor for all the front end stuff would be the least crappy solution. The second least crappy solution would be getting a 4wd Explorer/Ranger torsion bar front subframe and arms and just cutting, modifying and welding until it fit well enough. I think that solution would be overall cleaner than trying to fit a TTB into a chassis that really, really wasn't designed for it.
I wound up concluding that all things considered if I wanted to build something fun that dumping in a hot 302 and laying rubber everywhere would be the all around better option.
If you want a big floppy off road box buy a Cherokee. If you want a small floppy off road box buy a BII.