Super fast reply from Eurocharged.

"Yes sir! We have them in stock. Pulley/tune on a SRT6 is about a 50 wheel gain.
Just FYI, we strongly recommend injectors with the 62mm pulley. It tends to run out of injector in the last 1000 RPM."

So to answer my question, fuel mods will be necessary (IMO) to run the 62 mm.

The Dyno charts on their websites show a gain about 46 whp, so does that mean going from 65mm to 62 is only good for about 5 whp? I sent them another email as well.