Like I said the people you are hearing that crap from are idiots.
It's a bolt in deal. The 727 will bolt right to the existing crossmember. Get the right motor mounts and you are good to go. Headers are the biggest decision.
Few upgrades are recommended but they are bolt on also. I'd go bigger torsion bars if it's mainly a street car. If it doesn't already have disc brakes I'd put them on.