I'm with Ed on this one, don't do it. You reaslly should have more carbn to work with, unless you want to use it as hardware, and not as a blade steel.
If you use equal parts of two steels, take the carbon content of each, add them together, then divide by two. This will give you a number that represents how much carbon is available to begin with in the mix. There will be some loss in process (how much varies with your methods and tools).
5160= .6%C
1018= .18%C
total = .78
divided by two =.39%C at best, and this assumes no carbon loss in process. Result is not good steel for making blades, though it would make a knife if you quenched it fast enough then didn't temper it much if at all.
Use something else with more carbon for the other steel. I suggest L-6.