Just remember that pulling the cringle down, tight to the boom, is just as important as pulling it backwards. On my boat I copied a set-up often seen on big boats; The reefing line goes from the block in an angle to the cringle. At maximum pull the angle is such there is still backward pull. Someone suggested 45 degrees,that would agree with me. Through the cringle, on the other side of the sail, the bitter end goes to a fixture (a slider in my case) on the bottom of the boom. The fixture is more or less below the cringle when it is in its aft most position. There it provides maximum down pull and prevents the cringle from lifting off the boom. Having the bitter end below the boom not only allows the cringle to be pulled tight against the boom but it also provides sufficient space for the unused part of the sail. Suppose the reefing line is attached to some fixture on top of the boom right next to the cringle, that would crush you precious sail like a pepper mill because there is just not enough space left for the cloth to go.
Maybe it helps if you have a look at some pictures of my boat. (pdf alert!). Note that I have used an existing sheave at the boom end. (A modern boom end has two sheaves). A cheek block as you suggest is just as good. It is only that I like to have my reefing line inside the boom. If not you need to think of something to hold the reefing line up and prevent getting caught by it in a gybe or a tack. An unused reefing line is always slack and some day it will lash around your neck, usually when you least expect it! (Sod’s law).