Can a connection be established from copper wire to stainless steel bus for power connection?
I think you are way over thinking this. Take your copper cable and crimp an appropriately sized copper ring terminal onto the end. Then drill and tap a threaded hole in the stainless steel bus bar that takes a screw of a size to fit nicely in the hole of the ring terminal. Simply screw the terminal to the bus bar and be done with the job.

Obviously it is up to you to select the proper sized copper cable, crimp terminal and screw that are rated for the amount of current that you want to transfer into or out of the bus bar.