Howdy, Wolflobo. Glad to see you here. You're good to go with the Walker and the Spencer for sure. I'm going to have a list of approved and disapproved firearms listed in a sticky at the top of the front page by the time you read this. As far as clothing, if you intend to get into that aspect of it, basically just remember that we're pushing for a higher degree of period correctness than you'll find at most rendezvous.
By the way, I'll second Chaparosa's suggestion to post some photos, especially of your Spencer. I shoot an Armi Sport in 56-50, and love it.