One thing about stovebolt main bearing caps- - - -they "float". There's no dowel pins, or other means of holding them in perfect alignment with the block, so as long as the inside diameter of the block/cap interface is correct, line boring just might not be necessary. As the bolts are snugged up while installing the crankshaft, the cap (and the lower main bearing) tends to self-align with the crankshaft. That's particularly true if brass shims are being used to adjust the oil clearance.
Jerry
