if it's one of thekraven's awesome ROMS, he includes a flashable patch to use them on VM.
I advise using one of his, they're very functional and with the premade patch it's easy to install them.
yay, ZV4 baseband! it has fastboot enabled. if you 'upgrade' to any other available baseband, sprint or vm, you'll lose access to fastboot and probably not be able to find a working zv4 cab to get it back.
if you don't care about fastboot, there isn't any reason to worry about changing basebands except going to sprint baseband is trickier to do and if you don't follow directions exactly you'll lose your mobile data.