The best of both worlds is to have a large bore centerfire in the rolling block, and make an insert liner in .22 lr.  You can insert the liner and change the extractor, and breech block and have a .22 in your centerfire rifle.  You can generally get spare breech blocks for the conversion from Kenn at rolingblockparts.com

I have two of them done that way.  One, I had an original .22 rf block and I just used it, although I had to make a bushing to repair old primer erosion anyway.  The other, I had John King bush and rework for .22 rf.  I made the liners myself, by turning a steel case the size of the cartridge, and then bored it out and soldered in a liner.  

I use teflon tubing from McMaster Carr to center the liner in my rifle barrel.  Cut the tubing into about 1 inch pieces, and space them at unequal distances along the liner.  Move the spacers to tune the barrel; by trial and error you can find the configuration that shoots best.  My liner in my rolling block is capable of similar accuracy to my Lilja barreled Ballard.