I've been down this road before, first with a 1 3/4\" S&S, then with an Airspeed 1 1/2\".
Not saying you will have leaks with yours at first but after a couple re&re's, no doubt.
I tried the orange high temp silicone and that didn't really work for me, ended up slicing the swedged end in 1/4's with a hack saw only about 1 1/4\" and wrapping a stainless t-bolt clamp (turbo induction style) around to pinch it together....that works pretty good.
If I did it again i'd take the header to a muffler shop and slightly expand the inner tube to make the joint tighter.