Well it don't do me any good on this build but it looks like the 03-08 5.7 hemi 2.0" intake valve would almost drop in with a seat cut and finding a spring to fit the smaller retainer (possibly a GM 3100 V6 spring with very mild cams). It is just a tiny bit longer, maybe .020"

On this engine the larger diameter would mean less shaving of the heads and less compression, the bigger diameter, lighter valve and retainer would give me a little more power but I am after crazy compression.