later 4.0 into older jeep

Hello again, long time no speak.... My sister owns a 1992 Jeep Cherokee Laredo with a 4.0 H.O. and auto transmission in it. She's almost quite literally melted the motor down in it (melted head gasket, three pistons with vaporized ring lands, etc), so I'm going to swap the cooked 4.0 out for...