A 6.1 Hemi won't work, because everything is based on Mercedes technology.

If you want to combine a V8 with a MT maybe you can think about the M 113 E 4.3 litre Mercedes V8.
It's technically based on the M112 3.2 V6 engine but has two more cylinders.

If you don't have the skills to do it yourself i think the cost benefit ratio doesn't make sense.