Pat the Mercedes disc is the same as the TIII disc, the only difference being the oil groves. So you can run the Mercedes discs with the Mercedes lifter, and no modification is needed. I have some hard miles on my car with this setup, and no problems yet .I've used this lifter (Mercedes listed above) for a a few years in a T3. Works very well. Only difference I was able to decipher is that at the base where it contacts the disc is a slightly larger diameter than the stock lifter and doesn't align with the dimples on the lifter disc. My suspicion is that the dimples are there to allow oil flow into the lifter. To allow that oil flow, I made two very small cuts on the lifter base where it rides the disc to allow oil flow in and out.That looks very close in design to the Lotus lifter. The only thing is the Fiat lifter has the white seal on the bottom as does the Lotus lifter . The Lotus 16V rocker has a relief inside where the white seal seats and I imagine floats up and down during the lifter compression cycle. Usually when you pull the lifter out of the lotus rocker the white seal gets ripped up or just falls apart.
The Chrysler and the Mercedes look to have a metal ring guard toward the bottom of the lifter, kinda like a piston ring, or it may be more of a lock ring to keep the lifter from falling out of the rocker. I think you are familiar with that from another thread .
Almost have to get picture of Chrysler 3.5 rocker or Mercedes rocker to see if it has a relief inside of the rocker lifter cavity.
The lifter seems to be fine, although I think my cuts were a bit too big. At sustained high rpm in an autocross, I ended up getting a bit of clatter after the run. I believe the cuts were a bit too bit and allowed the lifter to bleed down a bit faster than it should have. Oil control in the pan is very good with a baffled, trap door pan and a windage screen, so I don't think it was an oil control issue in the pan. That, and I've autocrossed this set up multiple times in the past without any lifter noise. That being said, the Mercedes lifters have survived about 5k of daily driving, an autocross or two and were in the t3 car I ran in Hot Rod Drag Week in '13, which saw 1000 miles towing a trailer and about 12 drag passes in the 11's.
My plan had been to buy another set and tinker with the oil flow slot size but time hasn't allowed it. It's still on the list, but maybe one of you guys can tackle that sooner than I can.