OK, here is what I ended up doing. The stove is working much better now with a much stronger flame. If anyone has any opinion on this, please reply and let me know. The last thing I want to do is to endanger myself or anyone else.
According to the picture posted above, the orifice for the regular burner side is #55. For this stove I am using the regular burners on both side rather than using the grill. The LP orifices that were on the stove were #66 (.033") & #63 (.037").
On ebay there are plenty of #55 drill bits for just a few bucks. However, I do not have a drill press and was afraid I might wobble and enlarge the holes too much by using a hand drill.
Instead, I ordered (4) #56 gas hood orifices:http://www.etundra.com/Natural_Gas_Hood_Orifice-P1747.html?token=45894|||0|24|7|1|0
I wasn't sure when I ordered them if they would fit correctly, but they are the same size and thread as the old orifices. So I just screwed these on and flipped the regulator and things seem to be working.
These are .0465" instead of the .0520" of the correct #55 orifices. However, the flame seems plenty strong enough and I was happy to err on the side of caution in this case.
Again, if I am not understanding this correctly and what I did is not appropriate, please let me know. Thanks everyone for your help!