I have line bored several engines with different-size main bearing bores. It's just necessary to set up a cutter for each bore size, and either make multiple passes through the block, or have a boring bar with positions for several cutters and do it all in one pass. The trick to any line bore is to take a whisker-thin cut out of the block to minimize the change in timing gear or chain fit, and take most of the material out of the cap. I mill .010" off the cap mating surfaces first to shrink the hole, then cut it back round and the proper size. .008"-.009" is cut out of the cap and only .001"-.002" is taken out of the block.
Jerry
