Wes,

I'd put the holes at the corners of the base plate, around 3/4" of an inch in from the edge. I went and looked at the saw on the Porter-Cable site, obviously, you'll need to work around the "waffle-iron" vertials on the base.

I'd use some 1/4" stove bolt with locking washers and nuts. That way you can countersink the head of the bolt into your custom base.

Try the link below, it has some good information.

Hope this helps.

Aaron