Since the Cleric line have only 7 buff limit. You get one more at rank 5 and one more by using Token. I think you should careful when using them because there are too many buff and they will all cancelled out all your good one.
And about the stat you donāt need to be full support tho since every skill you have donāt run out too fast so you can go for around ~40-45 SPR, 80 CON so you wonāt get 1 hit kill from boss and the rest into INT so you can give out a decent amount of damage, and Heal a decent amount of health too.
In my experience currently level 156 and also a Chaplain my stat was also the same as I said and I never run out of mana, my health was also around 12k and still sometime over DPS other people.
But Priest had a Skill called Stone Skin which is scale with SPR, if you really want this skill I suggest 2:1 for INT:SPR. The only struggle that I have is when doing matchmaking, people keep overwrite my good skill I gave them such as Sacrament and Last Rites, I have to recast it continuously.