I'm using an LA727 in mine, you use the flexplate that came with the Hemi but need to cut the ringgear off the flexplate and (may or may not need to) waller out one hole so the tc from the 904(727) will bolt on, I had to. I'd like for B&M to come out with a flexplate to mate the Hemi with a 904/727 and variants.
I saw the S&P fuel system they used on the Challenger but I didn't think they sold it as a kit when I looked into it. They used a custom built tank, external fuel pump, vette filter/reg (for return line) and sent only one line up front. I'd be concerned about pressure loss on a single line to the front but that may not be an issue. I chose to go with Don's design at FBO for my setup; a sumped baffled stock tank, external pump, -8 to the front, regulator at the fuel rail, then -6 back to the tank. You will need a fitting welded onto the fuel rail for AN line. AFAIK the fuel requirements are the same crate or takeout (58psi).
Don't worry about the questions, I have plenty myself and if I've found a problem or solution I'm more than happy to share, please do the same. MP as an info source leaves a lot to be desired.
I'll be putting mine in the vert in the next couple weeks (barring any work scheduling problems), need to change the kframe first since the vert was a slanty and the TTI mounts are for a 68-72 V8 kframe.
