What ROM will turn my Verizon HTC One M8 into the same thing as the unlocked dev version?
This looks like what you want. Basically, any ROM that says it's a "GPe" rom or a "Google Play edition" rom will be what you're after. To get the Google Apps you'll need to flash a GApps package such as the ParanoidAndroid ones - you can just choose the "stock" package. Flash those after flashing the ROM and you'll have a pre-rooted, dev version ROM.