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

Most drill presses are going to ruin the bore no matter how rigid the base and structure because they don't have the correct type of spindle bearings to deal with the side forces generated by single point boring. The tool hanging out that far is going to wobble all over then grab and break something if the motor has any nuts. I'm all for McGyvering stuff if you have to, but it doesn't make any sense here. I think you'd be better off wearing out a couple of flex hones to do your overbore rather than modifying a POS drill press.