has anybody built there own blower manifold

Yeah, thats me.
You might want want to buy a 6-71 blower manifold and bolt a plate to that.
This way if you want to upgrade in the future to a 6 or 8-71 blower you have the manifold.
I got a 174 blower with a 6 rib belt and it slips. 10 rib belt and pullies are nice.