From the other post, it seems to me the combination is undercammed, undercarbureted, and has the wrong intake manifold to make 500 real hp.
But if your heart is set on all those parts and there's no ET goal or anything like that, give it a whirl, you may end up liking it just fine and the exact number won't matter as much as feeling happy with it and knowing it's your ideas.

Ignoring all that kind of stuff, 1 7/8 with a 3" collector, 3" headpipes into mufflers/2.5" tailpipes is plenty adequate and gives a little room to grow if you decide to go with more cam and so on later, to satisfy the need for speed.

Mine went 119 with that combination minus tailpipes. And I bet the tailpipes would have just made it quieter inside.

Being a believer in making the exhaust whatever size the collector is has led me to 3.5" exhaust, which I don't actually recommend to anyone. I had fun fabricating it, though, and the car sounds really unique. But like underdrive pulleys, which I also use, I always tell everyone else not to.