Problem:
I am using the thread wizard on mach3 and, I not sure which to use. I am making internal threads. It is easier for me to make threads from bottom to top. Should I use climb to thread? Or should I thread from the with conventional from the top down, even though the external treads I will threading onto it will be coming in from the top down?

Let me reword my problem:
I need help with conventional vs climb thread milling.

I previously made my first thread milling and it worked:
Internal, conventional

I am making another piece that needs to have the same threads.
However, piece I am threading is rotated 180 from the first.

Can I use internal convential to make the same threads? OR do I need to switch to internal climb?

I am not sure what you are asking but if you reverse the direction you will reverse the thread e.g. right hand would become left hand.

G02 travelling Z zero to Z minus will produce a right hand thread (clockwise helix)

G03 travelling Z zero to Z minus will produce a left hand thread (anti clockwise helix)

Graham