Mine had Schumacher tri y on there when I bought it. For the engine that is in the car they would have been fine.
I went with 2 " tti and they are in the car now. Overkill for this motor but I have one being built that can use them.
Header fitment depends on whether you are running power steering also. Tri y will fit with power steering,Tti will not with factory p.s.
Your motor would do well with the 1 3/4 Tti or the tri y's.
I'm leaning toward TTI, but they are not cheap for sure. Luckily Steve setup the Duster, before I bought it, with a new manual steering box and an upgraded bearing instead of the rag joint. It turns like no manual box I've ever messed with.
Just trying to get all the pieces together now and not make any costly mistakes in the process.