Your always trying to talk guys out of the job...lol
Sometimes to certain people the juice is worth the squeeze ..I personally have a love for 90s cars and will probably be in them for along time to come..birds Cougars and marks are my favorite followed by trans am camaro and the mustang of course ...I do prefer 94 on up models though..
It's called being realistic, the question is "how feasible will it be?", not "wouldn't this swap be cool?". I don't agree with MaddMartigan that an old car project would only be worthwhile for racing - I never go racing, I like tinkering even more than driving, and when I am driving I prefer it to be a car I tinkered on. - Where I agree with him is that the potential for what the OP wants, which is a driver, has the very real potential to become a project car, and project cars are have a horrible habit of never getting finished.
To me it seems missing and hard to find(i.e. MN12 specific) components will plague putting a 5.0 back in, and a complete rewiring will plague a 4.6/4R70w transplant. Finding a suitable doner car would almost be necessary now that these are uncommon at junkyards, and at that stage of things you have to question why not just drive the doner car?