I seriously doubt that the shop in Encinitas really knows much about setting up your gun. The only shop I've heard of in San Diego County that is said to be dedicated to Spearfishing is James and Joseph, although I have not been there myself.
There is a shop in Dana Point that must stock more Riffe guns than anyone, as well as many other guns. But like most shops, their main business is selling scuba gear and scuba training. They will be glad to sell you a Riffe gun too, but I doubt that you will run into anyone with the time, interest, or knowledge to help you set up or explain much to you. They simply don't do much spearfishing themselves.
But maybe I'm trying to push you beyond what you are ready to hear anyway. If you haven't done much spearfishing, then its hard to even know what to ask or understand the answers. That is perfectly normal.
Just know that the offer stands. I'll try to help with any questions that you ask here, and I'll be glad to arrange to meet with you if you would like that.
You just have to realize that you would have to listen to more stories than you might be willing to hear.
