i haven't used them but I have heard that there is a Mopar oriented shop out towards Joliet. I'll have to look around again for their name. Ive never built anything that "hopped up" so I have just used the local guys that do anything that comes in the door. I have been having a harder time finding one lately, due to the machinists getting old-- retirement age.... There's a decent one in Wilmington (a lil south of Joliet) the owner's son has branched out and bought out a long standing machine shop here in kankakee. I've dealt with the Dad and uncle before in Wilmington, got good service. Begler's machine. The son (also goes by that name) here in Kankakee, bought out the old long standing Albers Automotive, machine shop. My son has an "in" with a local diesel shop that uses them alot, and my son had a 360 built into a 408 by them and seems happy so far.
a lil far from home to work, have a hard time getting back by home to get to the local machine shop in time. I found one in Kentland IN, only 15 min from work, that has my slant 6. He's done other work for me, and so far so good. Newco Performance.