2008 Challenger 6.1 swap input

I talked to hotwire the other day about it and they basically recommended going with the 545rfe transmission and getting an ecu/harness kit from them.

He just messaged me back tonight saying he would sell me just the motor and to shoot him an offer. What do you guys think I should offer him for the 6.1 by itself, no paperwork on the 38,000 miles but we would be doing a compression test prior to me taking it home.