Are you sure you want to run 4x4 still???

That complicates the project a hell of a lot!

Although they did make a 4x4 E30 (325ix) they were rare, and i would think finding a set of front hubs/uprights from one will be hard.

If you went 2wd with a T5 the project would be as simple as some engine mounts, a prop and maybe some sump mods.

I can recommend using a company called autoprop for your prop. You could ask them to make a bmw/cossie hybrid out of your two props, but with their very reasonable prices it is usually worth gettting them to make a complete new one. Much better to have brand new UJs and joints.

My brand new 3 inch prop for my kit car only cost £120! Bargain.