Well we went from 65hp to about 225hp with that Cummins 6, and the torque is off the scale. One of the reasons for the 6 was it runs smoother than the 4 cyl Cummins. It's certainly overpowered for the Brill car, the automatic is smoother than the manual trans, and the Diesel fuel is lots safer than gasoline. BTW, we got the modified driveshaft balanced for high speed running. You should see the Brill joint on one end, and the 1/3 size of the modern U joint on the other.
All of the mods are reversible, so if you have the inclination of finding all the missing pieces of the old engine to rebuild it, knock yerself out....