o ring grouve is good place for silicone - that's how I mount water pump to block
silicone , then push o ring into grouve and bolt on , never had a leak , but then I've never put somthin together that leaked
gen electric high heat silicone is best stuff ever , but I can't get it anymore
I liked the fel -pro print o seal 2.2 h gaskets too - don't rot like dodge ones