I need to drill and tap a series of holes in the top of a used PM26 shaper to mount aftermarket guards and a stock feeder. My only experience of drilling into cast iron machines came in connection with attaching Unifence and Biesemeyer rails onto saws--and that didn't require much precision or any tapping. So basically I am coming at this with no background. I don't want to remove the top for the machine and am envisioning--correctly??--an approach using a portable drill and guide blocks to establish the correct hole pattern/spacing and keep the bit perpendicular. Guidance, advice and/or links to good threads or videos would be much appreciated.