I don't think by sampling the video at a higher rate of 60 interlaced, compared to the native 30 interlaced (technically 29.97) will gain you anything. Capturing at the native interlaced rate of the video is recommended on this forum.
As far as deinterlacing goes, QTGMC is the gold standard, and produces a 60p output from a 30i input. You can change the video back to 30p afterward. There's examples on this forum for that. However, it seems you want 60p, so you wouldn't need to add that step after QTGMC. QTGMC can be very configurable, or you can just use one of the various preset levels. It's time intensive, but is the best at what it does. A fair amount of avisynth plugins are required to get QTGMC working. Lots of forum posts are out there involving setup and usage settings. But the page on avisynth website is a great place to start.
http://avisynth.nl/index.php/QTGMC Use
Virtualdub in conjunction with Avisynth. You load a .avs file in
Virtualdub. The .avs file contains the avisynth code to open and process your file, including making QTGMC call.