I’m generally pretty happy with the results when I have to convert NTSC 29.97 or HDV 1080, 60i source to 24fps in Vegas… you may have to play around with things to find the best approach for your needs though, since there are hundreds if not thousands of possible ways to do it, from defining your project as 24fps and imposing that by brute force on your 29.97 source files or getting much more controlled and obsessive about it.
Bottom line, it can be done pretty much with as much control or as much speed and slop as you decide you need and have time for.
I’m speaking as a user of Pro 8.0c, fwiw. You might find more limitations in earlier versions or the more consumer-oriented sets that limit some features and support fewer codecs and so on.