Rolls Royce by name GM Allison by nature!
First ran in 1959 and qualified in 1962.
Good info
here. 50 years young! Check out some of the derivatives especially the twin pack!
It seems that the good ideas have all been cherry picked which is OK until you try to do it commercially.
Remember it took 15 years for the G2 to get a Type Certificate!
This aircraft is a prototype amateur built aircraft. A long way from a commercial version but a good place to start? Who knows and the best of luck to them.