Best thread sealant for exhaust studs into water jacket

Yes, the temp wouldn't be accurate, esp with the exh header or manifold right there. So it's all a guess really. I looked up the ARP thread sealer, that is 550F which is probably what I would prefer. However it is $30 here and that is a bit out of my budget, when I can get the Permatex for $11 delivered. Pendantic is a big word yes, and also doesn't exist, no offence intended :D . Pedantic is the word and I use it quite a lot because I think I suffer from Pedanticism hahaha, which is being overly fussy about small academic details.