Here's my '72 (RIP). Sorry it's only at idle. I was taking pics. They are Series 40 Flowmasters with tail pipes all the way back out the rear.
Thing is, the Series 40 sound like this if you are cammed up pretty good.
I'm going with the same mufflers and 2.5 pipes, headers. But milder cam. So I don't know what the new build will sound like.
I hope it's close.