thats a really tough question.....a really good engine that will work with your trans.....I guess it really comes down to what good means for you.... good for me would be an LS1, NV4500,Np205/Np203 doubler kit and d 60's front and rear...lol....anyway....i think your trans is gonna be what limits you....correct me if im wrong guys, but in 89 i think you have the peugot Ba-10 trans....and for lack of a better phrase...you'd be better off using it as a land anchor. I have the same trans in my wrangler now....if your gonna do 4.0 mpi swap your better off buying a F.I. parts vehicle...so you have all the parts you need...plus the peugot trans has the amc bolt pattern plus a 21 spline output shaft...and the ax-15 has a 23 ...hope i helped shine some light for you.
mike...