It's really easy to remove a non ambi safety and it's it's only other task is to provide a pivot pin for the grip safety. To remove it you simply lift up while cycling the safety between on an off. Note, the plunger that provides the detent may go shooting off into space so keep a close eye on it once you have a noticeable gap between the safety lever and frame.
BTW, I use a toothpick with one end cut square to hold the plunger in while inserting the thumb safety, this will allow you to get the safety in far enough to engage the plunger and do the on off thing while pushing it all the way home.
Now, about those ambi safeties. They aren't at all difficult to install but you will need some masking tape and channel lock pliers. Because most ambi safety systems have a hollow shaft on the left side and a fixed pin on the right side lever that is press fit into the tube for the left side safety lever. What you do is install the left side normally and get the right side started. Then you put some masking tape on both levers on the areas over the press fit tube and pin. Then you position the channel locks to they are pressing right over that common shaft and squeeze everything together. As for removal, that can be a royal PITA because you have to very carefully pry the right side lever up a bit until you can slide some plastic in on both sides to protect the finish on the frame. Then you gradually work on that right side lever until it comes free. I'll also warn you that there is about a 30% chance of breaking off the right side lever when you are trying to pry it free and for a really tight press fit the odds go way up. If you want to swap out the trigger for something different or tune the trigger break you will want to do all that BEFORE you install the ambi safety.
As for a source for parts like this, I prefer Ed Brown but Wilson Combat also has an extensive catalog of 1911 parts. You can usually find either brand in stock at Brownells.
