As a former body/frame rack guy, I'd be looking for an 18+ front clip to use as a donor. They can be had for about 3,000 from the parts farm, although I'm not sure about getting it down to Mexico. Surely you could source one from a salvage auction? There's no reason to try to pull this out if you're planning on doing the conversion anyways as the front ends are vastly different and nothing is going to line up if you try to homebrew it.Has anybody dealt with this before? Or do they know 100% if its different or the same?
However, if you decide to keep it as a 15, should be a pretty quick job. Congrats on the new project, I'll be following it!