I'm running them in my Duster. Sure was nice to start the car and just let it idle.
I did have to clearance my block to get them to drop in, but don't think it was Hughes' fault. It was a ridge or bump that wouldn't allow the lifter set to drop in on the passenger side rear cylinder. Other than that it was a straight install, no work required.
I'm running an OEM Magnum cam, so I can't help on the lift question.
Part of the reason I went to the roller lifters was to fix the pushrod interference I was getting with my R/T heads. The heads are cast much thicker in that area than the OEM heads, and them machined, and the angle they machine them for is one with a taller lifter. The flat tappen cam and lifters put the pushrod up against the head. I could have clearanced the heads, but I didn't want to and it gave me another reason to run the rollers.