Anybody ever take off the asv spacers on the exhaust ports and put the original header back on? If so, how's the clearance?

I dont think that will work. The angle of the exhaust will be off where it mounts on the tranny. You would need to either get some spacers or get another Y pipe that is made for use without those spacers.

It will hit the engine cross-member. Leave the spacer as it's iron, and you can tap threads for 7/16"x20 into it for a more secure fitment of the flanges. Also cut the threaded end off the ASV pipe and weld it up using a washer, etc. That will effectively block the port on the side of it.

 

GD