Grease up the bores and put them in storage. I woudlnt port them now until your sure what your going to build. I would go 4 mill for sure, but the type of porting who knows until you start building something.
I got 3 sets of cylinders in storage.
1 set of 64mm bore no porting
1 set of 65mm bore no porting
1 set of 66mm bore no porting but junk bore. (Big Bore Sleeve possibility)