First time replacing heads and weird gasket issue.

Would Black RTV be ok? Never seen non hardening thread sealant Thanks for the heads up though. :)

Black or red RTV is the only thing I ever use on the block front and rear walls AND the bolt threads AND under the heads of the bolts where the bolt shank and head meet.
I think/hope 4speedragtop told you that if using an aftermarket intake the pins for the intake should be removed.