Jeff, I have been thinking about putting one of the LL8 inline 6's into one of my old trucks. I haven't found a direct manual transmission to mate behind it, but I would imagine finding an Chevy Trailblazer 2WD would be a good donor and would give you the 4L60E trans already matted to the engine.... You could probably swap out to the 4L80E trans and a dually rear end out of a 1 ton chevy inexpensively...
Just something to think about. The LL8's are close to 300hp and I think would be cool to stick with an inline 6! It would also probably turn enough RPM to not have to swap out the rear end and get you 65-70MPH.