Now that I think about it, you could put the smaller head on the even bank and let it go. It won't even know it.

I had engines that ran very well come into the shop with 2 different heads on them. this was an issue in the late 90's early 00's with Canfields from jegs. The order puller would pick the heads up and not check the boxes. guys would bolt them on and run them.

We obviously fixed them, but when you tell someone their heads don't match they think something is up. But I have seen the mistake many times.