What happened to the 14t you were working on earlier? Did you get rid of it to get this baler, or is this a project piece?
What you are up against here is designed obsolescence. JD planned on pricing these parts radically to force you into another baler. This is the design flaw of the 14, 214, and 24 series balers. When that block is that far gone, and that one is in really really bad shape, usually the rail it runs on is shot also. When JD made the 224, they went to bearings on both sides of the plunger where you have the wear block. With the new design of the 224 the only wear block is on the front edge of the plunger where there is very little weight or wear on it. Look it up on JD parts on the 336 plunger. JD still uses this design today with the bearings.
Depending on how much hay you do, and how good you are at agro engineering there is something you could try anyway. First you have to make sure the rails inside the baler are straight and worth putting all this work and money into. If you can get that block ground so that the new surface is flat, you could shim it to the correct height and weld it in place. OR you could get a block of steel the size of the replacement part and weld that in. Metal will not be the same, but it may work for a good while if you only do a few hundred a year. These would be one time repairs, and when it wears out again the plunger is done. If you are only doing a few hundred bales a year, maybe worth thinking about.
In the mean time, start hunting for a nice old JD 336. You will not regret moving up to the 336. Look hard enough and long enough, and you can find them that need work for 500-1000, or have been parked in a barn since grandpa stopped baling 20 years ago. Keep the knotters out of this baler if these are the ones we got working in the spring. They will fit the 336, and a 336 is much more repairable than a 214.
JD learned alot about how to make a good baler from the 214, 14, 224, and 24 balers. By the time they got to the 336 they really had it figured out and it really has not changed much since then. Another good one to find, but fewer are out there is the 224t. It has all the basic design of the 336, just a generation older, but a great baler.
As to knives, I agree with AKFish, he is right on. Sharpen the suckers, make sure you mount the stationary knife on the bale case GOOD and tight, hammer blows to the head of the plow bolts holding it in, and clean out really well behind it. As long as it cut fairly clean, go with it and save the money for a newer baler.