It could be added on op, that before pull you can get free 8 hp by using holy pvp set: 5 hp before pull, inq, 3 more and swap pve gear back on and start with full 5hp. Normal bs version should also work, so you can do this with little effort.
where exactly were you planning on getting this hp before pull? i dont think any bosses have at least 8 critters running around for you to pre-hp.
i am 99% certain when changing from holy spec to ret spec your hp is removed, same as your mana.