sandwich:
I've never tried using the .mve files from FreeSpace 1 in FS2. BTW, I assume you're referring to the cutscenes, as those are the only .mve files I know of. I guess it depends a lot on whether or not the .mve file format has changed and how you could get FreeSpace 2 to read the .mves from a different location than the ones specified (cutscene.tbl, perhaps?)
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It seems as though there's a bit of a discrepancy surrounding how to port the original game over to the sequel. From my point of view, a direct port or conversion of the FS1 story and universe to FreeSpace 2 would entail the moving of FS1 ships into the sequel's table files, complete with models and textures, in addition to the mission editing. I don't think that'd be too hard, as I'm 99% sure there's already MODs out there for every FS1 ship to be made available in FS2. Converting weapons wouldn't be too difficult either, and we could even give them better graphical effects than those that are seen in FS1. Music and voice overs from the command briefs and debriefs would be no problem either.
A port of all the missions, and nothing more, would be slightly easier than the above method simply because it wouldn't involve converting any material except the missions. You could have FS2 ships, weapons, beams, flak, shields....whatever. Obviously this would destroy the true FS1 experience, however. Like I said above, it'd be more like "The Great War in 2367" (yes, I know I said 2362. SMACK me or something). And, as Setekh noted, many of the missions would have to be retailored because of the gameplay implications beams add.
So, let's refine the details a little. What specifically would you like to see in it? Should we do our aboslute best to recreate the FS1 atmosphere, complete with menu and main hall graphics and other FreeSpace 1 execlusives? Or should we ignore that route and modify the original FreeSpace 1 missions would beam weapons, flak, Maras and Herc IIs?