Nisei,
I am not sure how to determine the msdash version but I can tell you that hex editing it takes less than 5 minutes. Just make sure to rename or copy the original xbe just incase something goes wrong with the hex editing. Also make sure you are not set to boot to the msdash by default when your mod chip is on. This way you can put the original back if there are any problems.
I am sure if you tried now you will have the MS dash displaying in 480p within 10 minutes.
FTP in to your xbox and copy over the xboxdash.xbe to your computer. Make a copy of it and name the copy xboxdash.bak Open up the orignial in XVI32 found
HereClick on Search --> Replace-->
Then type
C7 46 28 20 00 00 00
and make sure hex string is selected
In the lower section put in
C7 46 28 00 00 00 00
Make sure hex string is selected
Click replace all .. You should get a popup window that says one occurences 1. Click OK then save it and copy that back over to the xbox overwriting the original xboxdash.xbe
If it fails you still have a copy of the original (Remeber the xboxdash.bak)