Respec holy at 70 for PvP

If you don't want a pally, don't level the pally.
If you want a pally, it's a viable tank and a viable healer.

Step 1: decide what you want
Step 2: figure out if leveling a pally is inline with your wants
Step 3: ask forums for advice about your idea

I think you skipped step 1 and 2.