Transcode the H264 to ProRes.
Some people use 442 LT and find that totally adequate (Philip Bloom usually uses LT according to his blog) others use ProRes422.
You cant really see any quality difference between 422 and 422 HQ (although some Colourists prefer HQ footage if grading) I tend to use HQ if I am going to Color but have the luxury of lots of drive space over fibre but to be honest no real gain) and 4444 is overkill and just a much bigger file for no gain in quality.
best wishes
Neil
http://www.patience.tv