I dont know about putting a big block mopar in a z but I have a 396 big block chevy in mine fits quite nicely I might add. I,m not sure what the width of the mopar big blocks are but I bet it will fit except the Hemi heads will probably be to wide. break out the tape measure and get with it . Its fun not having what everyone else does I will email a picture if you like the one I have is to big a file for this site.