Go with the K5 and 50-135 a combination I use at events and weddings. Usually I have a flash setup to go with it. Your best option is to bounce flash if you have the chance. bounce flash and 50-135 is a magical combination.
Originally posted by jsherman999
For wedding work I'd probably rent/buy a 24-70 2.8 for the D600.
be sure you have your head around the gear before hand. You may be familiar with the camera. I find in general camera controls on other brands are a poor match to Pentax. I don't know the D600 but lesser models finding the ISO adjustment without a manual is a nightmare.
If you go with the 24-70 which seems like a good choice, find out how the corners distort at 24mm. Nothing worse than getting the images on the computer and the heads in the corners are stretched and they look like aliens.
Myself I would prefer a pentax K5 and maybe a 16-50 however I actually use primes between 10mm and 50 mm