Is the Cummins 727/518 bellhousing bolt pattern the same as the small block pattern?

No,just cummins. And v-10

The 518 I believe is just cummins but the 727 used an adapter plate from what Ive been told but the certain parts inside need swapped as they are specific to work with the low rpm of the cummins

I just called a friend that knows all there is to know about Cummins and other Mopars.

He confirmed that the V10 shares a bellhousing with the Cummins when the adapter plate is used.

All the Cummins use the adapter plate, but the plate is different for each generation.

And unfortunately it is not a small block pattern bell.

The Viper V10 uses the same bell housing bolt pattern also.