Those old two-cycle diesels will be hard to find. 8V71 is the model of the engine; eight cylinders with 71 cubic inches each. They are around, start by asking diesel mechanics.
Dave
Actually, the 318 Detroit is in teh 53 series, and is a 6 cylinder. You can get a 6-53 inline, or a 6v53 v-6, which is what they used in busses a lot back in the 60s and 70s.
It won't be a powerhouse, as it is 180 horse naturally aspirated (unless you consider the 2 psi blower to be other than natural, but those were for scavenge effect, not for power), but they rev quick and sound cooler than cool.
That said, I would imagine you could soup it up a bit with turbochargers and big fuel. Maybe 250 to 300 horse in a light duty application??? I dunno. Would be cool to see.
if memory serves, I remember seeing one wedged into a 70's ford 4x4. They aren't small engines by any means. Make a 7.3 powerstroke look like a tinker toy.