You would not want the UIM to sit closer to the valve covers.
Plus the fuel rail and injectors wouldn't fit if you took off that much LIM height.
How would you mount the UIM if you milled the top down?
Where would the injectors mount if you milled the bottom?
Let's say for argument's sake it did fit and you also welded on new injector bosses.
Your change in rpm range from shortening the runners 1" would be fairly small. Probably make the ideal range a couple hundred rpm higher. The runner length from the common plenums would be about 6% & 10% shorter respectively.
It might make sense for a high compression engine with some custom cams.
However without other considerable changes to the engine the higher powerband would be wasted and your midrange would suffer.
I'd take it for granted you would completely remove the butterflies with an engine like this so we won't comment of the low end.
