Indeed what I'd seen. Not very big, but the 4.0L wasn't built for boost and only supports 6-8psi without changing up pistons and rods. It was unique that it was complete including a working tune.
Today's options are really different both in the players and the ability to tune the system. You could do a 48V electric system and e-turbo with MAP and TPS inputs. Or stick with a traditional turbo/intercooler, add a 2 or 3 atm MAP sensor and remap the programming around it with HP Tuners. It seems like people struggle with the scaling and transition on and off boost with these, but I'm sure it can be gotten right with some patience and good logging drives.