I have an H2AD in my RV-4. The only difference on the mount for a TW aircraft is the upper cross bar because the H2AD has a unique accessory case. I'm sure Russ McCucheon can advise you, as he built most of them. It would be fairly straightforward to convert a standard mount. There are several 6/6A guys with H2ADs, and maybe someone will chime in if there are issues with the sump, but I doubt it. The bottom of the engine resembles all other O320s. You will have a dipstick location change from the VANs cutout on the upper cowl because it will not line up. I built my baffles because the standard kit while adaptable, aren't going to fit. All standard exhaust systems should fit the H2. See the pics of mine in a -4. I used a Vetterman 4 pipe. I run dual electric fuel pumps and machined the corners of the mechanical pump and governor bosses on the case. I built my engine myself, and it has proven to be a great engine.