I've got 2 questions. First, what aftermarket recoil spring do I need for an ultra Kimber? Am looking at Wilson and what pound rate do I need?

Second question. Is a "drop in" grip safety really drop in? Or will I have to do some mods on the frame? The bobbed safety on the RCP is cut at a downward angle so that when I hold the gun the beavertail cuts into the webbing of my thumb after 150 or so rounds. Thanks for any info

Not sure what size your model is, but is its a full length 5" 1911 a 16lb will do. If its around a 4" barrel, then step up to a 18lb. If its smaller yet, then 22lb. Might check with Kimber to be sure.

As for the drop in, it should work as long as you don't have the Series II with the grip safety that acuates the firing pin block.

The only fitting is the lug on the grip safety that contacts the trigger bow. It will have to be fitted to allow proper release and blocking of the trigger.

It's a model II with a 3" barrel.

The only way an aftermarket grip safety will work is if you take out all the firing pin safety parts...........which I don't recommend.

You may be able to have someone blend it better to the frame & your hand, of course that would require refinishing.