It seems like you may be trying to reinvent the wheel. However, I feel there are a few parts of that design that may be worth keeping. At first glance it seems as though the 450 rear sub frame is nonsense, but that allows you to run the 450 style seat which I would love to see. Also I do like the fact that you want it to be able to just accept 450 front end components. That makes parts availability greater. One of the bigger issues with the LSR and Laegers frames.
Basically I think you would be better off having a stock frame cradle section to build off of. Maybe some guys think different, I guess it would just depend on if the builder wants an existing cradle section or start from scratch. The banshee market is due for a readily available long travel frame. After seeing the stuff coming out of Turbo Chassis ( stock look alike ) I think you might be better off trying to work it out with Jordan. If he could make a modern frame that takes 450 components and rear subframe and seat sections, for under 4k, that fucker would never see the light of day. Best part, whoever does it that way doesn't need to build everything from scratch which makes it faster turn around and cost less. Plus guys like Jordan or Chris at Wheelman already have everything off the cradle jigged up. Good luck and post the results. This is one of your better ideas..... Needs some tweaking, but it's a solid start.