There ARE options to maintain proper speed AND reduce the flicker.
The key to the solution is a (free) video editing utility called Virtual Dub
http://www.virtualdub.com/
You would capture the video while running projector at 24fps with flicker and then reduce flicker in VirtualDub, or, preferably, sync the projector to 30fps and then adjust the frame rate in video editor to the proper rate that your film camera used.
Speaking of a digital camera, if your old film footage is precious, you may want to rent a high end camcorder for a weekend (a 3-CCD model with 1/3" CCD's or greater). Find out what your local video rental shops have (if any), download the manual in advance, and see if you need any cable adapters.
Keep in mind that your ultimate goal (which VirtualDub should help you accomplish) should be not 30i (30 fps interlaced) footage, but 24p (24 fps progressive). The latter compresses much better in MPEG2 resulting in smaller or higher quality files per given total file size and video running time. Besides flicker removal / reverse telecine, deinterlacing, and frame rate adjustment, you may want to experiment with gamma / contrast / brightness / video noise reduction filters available for the Virtual Dub.
That's the video part. The audio part is just as important. You may want to normalize (i.e. optimize levels), parametrically equalize, and reduce hiss / noise in your audio. For that I highly recommend CoolEdit 2000
http://www.syntrillium.com That software is very inexpensive (be sure to also get the advanced noise reduction plugin), and there's an eval period when you can have access to the features on the free download version for a limited time.
Good luck!
Alec