I'm contemplating sleeving a block, if possible. The factory bore is 3.91, with a max allowable overbore of .060. Bore spacing is 4.46. 4.125 bores would leave .250 between cylinders, which I'm told would be as tight as I'd want to go (I'd like to confirm that, BTW, as the source is only semi reliable).

Does anyone know who supplies sleeves? How about a point in the direction of a shop that's capable of performing such tasks, as well I'd certainly appreciate some light.