Trying to do this now by drilling 2 x 5/8 holes through the top of an ex-saw-bench which is now a sturdy work-bench, the mag drill won't look at it, gas doesn't seem to be the answer, so what next?
How thick is the top and what's it made of? Steel?
5/8" isn't a big hole. A 5/8 bit with a turned down shank on a 1/2" drill should be able to cut that with no problem.
would imagine it being cast iron, no foreseeable problem, start with a small diam drill and work your way up to 5/8"
I did a Spindle Moulder a while back drilled and tapped for a Ring fence.--with a battery drill. It was a big bolt, 15/16mm.