I'm thinking out loud here, to have a rear shock built to work with a no-link swinger is going to be more expensive than a conventional set up, and here is why. The linkage on a stock style banshee changes the motion ratio of the rear suspension through the travel providing a progressive ride and maintaining good ride quality over small bumps. So to run a no link set up will require significantly more spring rate to produce the same wheel rate, but to maintain the small bump ride quality is going to require a multi rate spring set up which requires more packaging length which could to some extent dictate the rear frame and suspension pick up points. Furhtermore most top level shock builders are very familiar with the standard banshee rear suspension configuration so it is very easy for them to valve and spring a rear shock to your specs because the only major variable is swing arm length. Without your shock builder being involved in the rear linkage changes and possible frame changes made to the rear suspension could possibly require you taking the bike to them for measurements. Again I was just thinking out loud here, call your shock builder and see what they have to say. Good luck with your project - it sounds like fun, and please post some pictures for us to have a look at, I ride a purpose built dune bike myself.