Turn a small drill press into a Bore/ Hone. Bolt it to the top of your engine block & do your own machining .

Two thoughts:

1) I tried using a vertical mill decades ago to bore a B&S single cylinder block. Disaster. Couldn't get the block mounted rigidly enough and the tool chatter was unbelievable.
2) I worked with an excellent mechanic years ago when you could get 0.005 over pistons who would use a hand cylinder hone to open the bores up. But he knew what he was doing as the bores were straight when he was done.