we are guessing because we don't have actual numbers of all the dissolved solids in the water. even if we did have numbers, the anion resin tends to be tricky - kind of have to try and see what happens. one thing to keep in mind, is that both cation and anion resins remove what you are intersted in and then all of the other similar ions that you may or may not be interested in removing. most of the positively changed ions that get removed by the softener with Ca++ are good to have removed (Mg creates hardness too, Fe and Mn stain, etc.). Same with the negatively charged ions - drinking nitrates, sulfates aren't good either but the one thing that anion removes that is beneficial is bicarbonate. its beneficial because it controls changes in pH which can affect your plumbing. one thing also to remember is that corrosion isn't just pH, its a combination of things. LSI is a better measure of if the water is corrosive than pH alone. some thoughts:
if you keep the order softener -> anion - > neutralizer, I would just point out that 2.5 grains is not particularly hard so some would probably deem that acceptable. however, you would likely have hardness buildup on stuff over time, may have to replace water heater more frequently than most, etc. with the neutralizer after the anion, you have acceptable pH and bicarbonates would be added back so LSI would likely be positive, but not sure how positive and too positive is bad too. best way to check would be to use the LSI index of that water to see where it falls for deposition of calcium.
if you change the order to neutralizer -> softener - > anion. i think you will probably be below 7 after the anion. But even if you still remained with a pH above 7, you will have removed most if not all of the bicarbonates from the water by the anion leaving you with a water that can very easily change pH (bicarbonates are the alkalinity/buffer). so even with a pH above 7, I would bet that the LSI would be very negative and you would still get corrosion. if you go this route, I would definatley look into soda ash injection after the anion which would both raise the pH and get you your bicarbonates back all without adding additional hardness (Ca++).