Mike Hill Plasma Table
I attached three photos of my initial test with .5" plate. The test hole was .75 inches.
 picture from the front side just after cutting
 picture from the backside before dross removal
 picture from the backside after removing the dross with a metal scraper.
The dross was very lightly attached so removal only took a few seconds.
I measured the hole from the front side with calipers and the cut was within 1/64" of an inch. The backside was within 1/32". The plasma arc creates a natural bevel so the backside will always be slightly smaller. If you needed more precision than that we could cut the holes smaller by 1/32" and then chase them through with the correct sized drill bit. With most of the material removed this should be a pretty quick operation.
If you need any parts cut let me know.