3.6 in A-body
Never mind I found what it looks like.
It is very similar to a Honda j35-37 v6 integral exhaust outlet.
I bet with some creative work you could use the Honda factory headpipe and it is a nice flowing, very tight radius 90 bend. And it has an 02 bung right up top. They are plentiful at the junkyards.
Just a thought.