Just took a look..I used a 3.5" hole saw for he oil plate. Then camfered the edges over with router (IMO just less of a chance to catch somthing) With that said make your hole whatever size your Oil filter wrench is. Theres enough clearance for a 4" then your into the metal backing on the iron balticyep I cut already. Looks like crap but you can’t see it without being under it.
In the stock screw holes?
not sure I understand.
you have the IB over them. You lined it up well enough or did you route it deep?