Cost is not the only factor, the other one is time.
Merely getting an old, broken vehicle back on the road is lot of work. Completely restoring a vehicle to like-new is an order of magnitude more work. Adding in an equipment swap from one version of a model to another (maybe auto->manual swap, or V6-V8 swap) is again so much more work.
Complete conversions like this take an insane amount of time. Probably months of time working on it full time. Part time, you're looking at a multi-year project. There is going to be a lot of trailblazing going on here, and there might only be 3 people in the world who can help you answer your problem.
Merely getting an old, broken vehicle back on the road is lot of work. Completely restoring a vehicle to like-new is an order of magnitude more work. Adding in an equipment swap from one version of a model to another (maybe auto->manual swap, or V6-V8 swap) is again so much more work.
Complete conversions like this take an insane amount of time. Probably months of time working on it full time. Part time, you're looking at a multi-year project. There is going to be a lot of trailblazing going on here, and there might only be 3 people in the world who can help you answer your problem.