Yes, it's straight forward to drill the 30mm hole. Just drill it to the correct position. It's ok to use a XR2i block too with changing the pistons. Then you will need to drill the oil return to the side of the block. The place is there in the block, just needs to be drilled out. I'd say drilling the 30mm hole is far easier if you have a suitable drill bit. A "Christmas tree" like this with a 30m final diameter will be ideal for the job if available.