I currently run Manley Super 70s that are 6.935". No problems as of yet. Of course that's a lot shorter than what your hoping to run along with Manley not making aluminum rods anymore. So if I was to go with aluminum I would say GRP. We have a couple sets in the shop and they are a nice piece!! For pistons we have been going with JE lately. Pretty easy to get a custom piston made. Other than that I couldn't say much more. I've never dealt with or been around your proposed combination (well the 11.1" deck and 7.1" rod)..