i would just buy a new gasket to be safe, u never know wut could happn if u use your old gasket, i know this wouldnt work on an exhaust application, but before my dad died we always used to work on the gas guzzlers like 350's SB 440's and such and instead of spending money on new gaskets for like heads, we would use a high stress sealant, i forgot wut the exact name of it wus but its perma- sumthing maybe perma-seal im not sure, ..................just tryin to help