I don't know why you're getting all this advice to release anything - that's not actually 4:3 or 1.37:1 (aka Academy Ratio) - without anamorphic enhancement in 2007. Maybe it's the lack of a real DVDSP update that's made us all lazy. 😉
Personally, I would try not to scale your 4:3 master in an anamorphic timeline in FCP. Instead, make use of Compressor 2 (or later) and Frame Controls to do the upscaling whenever possible.
I had to do what you're asking once, but for a 1.66:1 project. Based on that, here's what I'd recommend:
- Create a new 4:3 sequence
- (Optional) Alter the background of your Canvas to either of the Checkboard patterns
- On V1, drop in a Color Matte and adjust it's color to strongly contrast with your footage
- On your Color Matter, drop in a Widescreen Matte and adjust it to 1.78:1
- Place your 4:3 master on V2 and scale it down until it fits within the frame created by the Color Matte on V1. I'm guessing about 85% or so?
- Disable V1
- Instead of rendering and exporting a QT movie, to maintain the highest quality, I'd suggest marking off a key portion (perhaps no longer than 2 minutes), then File > Export > Using Compressor
- In Compressor, adjust the settings how you like, but be sure to:
- Alter the movie to 16:9 (duh!)
- Turn Frame Control to Custom and set both Resize and Deinterlace to Better (not Best) and adjust the Anti-Alias and Details settings to, say, 3 and 9, respectively.
- In the Geometry pane, adjust top and bottom crop values by 60. If your default is 2 and 4, make it 62 and 64. If it's 0 and 0, make it 60 and 60, etc
- Submit your encode. It will take a while (even for 2 minutes, in most cases)
- Evaluate your encode for the correct cropping (you might have to go back to FCP and adjust the scale values and/or centering) and whether you need to adjust the Anti-Alias and Details values in Compressor. Or, quite honestly, you might not think this is worth it. However, if this is a disc meant for replication, it usually is.
Personally, it takes me a few passes to get things right (Anti-Alias and Details being the hardest to pin down) but it's always worth it...
Let us know how it goes.