Raph, I used a Melling M29 oil pump on my 216/235 crank conversion. It takes some work on the connecting tubing to make it work with the 216's oil pickup.
HERE is my thread on that conversion. I bought the oil pump from RockAuto. Just search for Melling M29 in their web page.
I see that you have the crank, connecting rods and cam installed. Did you have interference with the cam and rods? I did and wound up grinding clearance flats on the cam to match the position of the same flats on a 235 cam.
This post shows what I did to take care of the rods hitting the cam. The whole thread covers my conversion to a 235 crankshaft.
re: Drilling a 216 crank for pressure oiling to the rods. That would take some pretty exact drilling, as the 216 cranks have a BIG hole extending into the crank pins from the side. If the oil holes hit that, then it's over for that project.