For carnac west, chitins 7 is definately better than FP +8s.. because theres no rare FP weapon defences on your server, however if you do prefer a higher HP build opposed to a higher AC build, u could stat so you could wear +7 or +8 DD chitin helmet, and then the rest of your armours you wear FP +8.
you would also have enough stats to wear chitin spear defence gloves, sword def boots or w/e, but NOT club defence pauldron and axe def pads this way.
But IMO, id still pick the chitins +7, the difference in stat points is very little, but chitins give more AC which is pretty important to priests, and the extra poitns in INT will never hurt.... since aas someone on these forums once said (i think it was JDizzle?) a priest can never have "too much mana" or somethign along those lines.
The reason why FP build is really common on the older servers is because they have rare weapon defences which make up for the loss in AC. The DD FP helm is +6/25 and the other spear defence pieces are +5/20, which is quite a bit more than the +7/15 chitin DD helmets that are out on the newer servers.
If you really want higher HP then maybe just use FP +8 gloves and boots? and the rest of the pieces use chitins for the higher ac? since theres only 8 AC difference between the gloves or boots (comparing fp8 to chit7) but then the pauldron has 23 AC difference and the pads has 17! which is quite a load~