Will a '90 LTD 302 work?

For a VERY mild, as in utterly tepid and uninspiring and blah motor, sure. Otherwise, pass on it.

Crown Vics, Town Cars, and Grand Marquis ("Panther" platform) cars, as well as Fox-body T-Birds and Cougars, used the lo-po version of the 5.0 that had crappy heads, a lame cam, flat-top pistons, smaller throttle body, more restrictive upper intake, and smaller injectors. Even stripping it down to the short block, you're still stuck with flat-top pistons, so your cam and valvetrain choices are pretty limited. About the most you could hope for one is to throw on a stock H.O. top end (heads, cam, intake, etc.) and a full exhaust, and you'll be on par with other stock 5.0's, but that's about it. If you swap out the pistons, then everything else left is exactly the same as in an H.O. motor, but at that point you'll have so much invested in building it up that you'd have been better off starting with an H.O. motor in the first place.

Look for a 5.0 motor out of an Explorer, Lincoln Mark VII LSC, MN12 ('89+) Thunderbird or Cougar, or F-150 as a better starting point.
 
Meh. Dogs require too much time and attention. Cats are easy. Leave out food and water, and scoop their poo every now and then, and that's it. Every once in awhile, if they're feeling generous, they'll ALLOW you to pet them for awhile before launching off your belly and leaving deep, bloody gouges in your flesh to show their thanks. Cats are metal because their love is so brutal. :rock: