that tranny is a T-5... it can only handle about 300hp... as long as he doesnt beat on it or it doesnt hook up on a hole shot he will be ok. and if he did do a auto conversion i would use the 4L60E, 4L80E, 700R4, or 200R4... TH350-400 and powerglide are not a good daily tranny due to lack of OD.