I renewed the RTV on the 2ndry cover etc when I was in there a month ago.
Although I must admit I only left it a few hours and not 'til the next day.
I reused the old valve cover to head gaskets with a view to getting new ones and having a go later whern they come in.

Later that week I had the plenums off with a view to doing a reconnaissance run on insulating under the SC. I warily reused the old gaskets.
I suspect it is those since the spatter (photo) is on the top of the 2ndry cover and angled as if it was sprayed form the plenum area rather than seepage/crawl.

I had heard (or I could be wrong) that someone had actually added spacers to the plenum....interesting idea - increase the volume and possibly add some momentum to the incoming air pressure.

Finally getting off my fat as$...
https://www.crossfireforum.org/forum...-gb-150-a.html
lowers AIT by lowering heat transmission up from the intake manifold to the plenum.
I suspect it may also be an advantage to add them to the intake/head contact surface as well.