Just an update.
I did the same mod to my new marker. One thing I did different was use an 1/8th inch drill to start it as it was a lot easier to get through the metal of the pump. I then moved to a 5/32 drill bit. Again though this is only for my certain metal rods I use as it may vary depending on the material you use. I forgot to bend them to have some friction tightening. I don't think it will matter but if you remember to do it I would!
Here it is on my new marker!