I'm finishing up a set of custom stainless steps for my brothers 69 dart. We tried 1-7/8 TTI and
an old set of I think hookers. Neither were within a mile, tubes ran right over the spark plugs.
I don't think we tried any w2 setups. Between the raised port and 4 spd setup just decided easier to do stainless.

We do have a spare set of flanges 3/8 ss if you need a set.