If you have the room to maneuver, the 77 on the K-1 would work in any light... while the 20-40 in the K-3 would get the wider shots, but not so wide that people would look distorted. Having the 70-200 at hand if you get stuck in a place and need the different FLs would also be handy.
Higher FLs is where you'll need higher shutter speeds (and higher ISO to be able to do that), so having the tele(s) on the K-1 is actually the better approach, I think.
Having a 2nd shooter, IMHO, is far more important than the decision about what gear to use, by the way. I only do small events as a gift to friends, but if I ever did a wedding, I would not do it without the 2nd photog. It's too fast and you can't keep moving around all the time, but you can't take the whole wedding from only a couple of angles. Having one photog, for example, focusing (literally
) on the bride, unimpeded, as she comes in while the other makes sure to get all the reactions from the groom, is priceless.