Yikes, do you have to trade? I mean, can you save for another 6 months and buy the LCR outright? Can you have a big yard sale to raise the funds?
I ask because I regret most of the trades/sales I've made. If you have any attachment at all, and if you like them even a little, it is highly likely regret will set in at some point.
I've tried to be VERY careful about what I trade or sell. But of the 5 trades/sells I've made in the last 5 or 6 years, I've had solid regret on 2, no regret on 2 and I'm on the fence on another but I'm starting to wish I hadn't sold it as well. The only times I've not regretted it were when I immediately replaced the gun with something similar that I just plain liked better (like my Taurus 94 for a S&W K-22, DUH!, or my Springfield XD9 for a 1911).
If you are dead set on trading, think long and hard about which you may end up regretting the least. Neither gun would be particularly hard to replace, though 64s may take a little more time.
If it was me, I'd keep the 64 simply because I am a revolver nut, and the 64 is a mighty fine revolver.