Any old Windsor block will drop right in. But as it's a four-cylinder, why not be amusing and put the SHO turbo 2.3 in it?

1999 Grand Marquis LS HPP with PI intake manifold, mild J-mod, Class III hitch, KYB PI shocks.
2000 Grand Marquis GS with no options and mild J-mod - Sold to Father-in-law