I realize its no sword saw but have you seen the
Prazi beam cutter
I have one and it works well, I don't use it all the time because I don't have the need always but I got it a few years ago when I had some 14x4 engineered lumber to cut, it got the job done
If your gonna need it often I might reccoment buying a circular saw to permanently mount it to they make them to fit all different saws
John