To tap or not to tap?

[HAULN-SS]

For the record...I know how a freakin tap works. My question is now do I make them threads the same size to re-use a stock o2? I'm thinking a chaser will do little because the threads looks really far gone. If I tap it out to a larger size I will have to find an oversized o2...get me? Deersty...what kind of tap and die set do you have that goes all the way up to those huge sizes? I'm pretty sure something like this would require some sort of extra large specialty tap.

i have used a 2" dye before - I have access to one actually. I am assuming there is a tap that goes with it somewhere as well.