For some reason, I'm not sure what type of concentrate that ratio creates. It could work.
I usually go with a method of making a simple syrup (1g sugar/1 ml water) and adding the concentrate to make a flavored syrup.
I like to re-use torani syrup bottles, which are 750 ml (25 or so oz.) What I would do is to use 23 fl.oz water and 26 oz (weight) sugar, heat that up to make a syrup, let it cool a bit as not to boil off flavors and add the 2 oz of concentrate since it's replacing the remaining 2 oz of water.
Other times, since it fills up the bottle... I fill the bottle to the brim with white cane sugar, pour in 23 oz of boiling water and finish it off with 2 oz of flavoring and cap it and give it a lot of shaking. I find though, that this is kind of a pain and the sugar clumps up a bit and requires more shaking than the simple syrup method.
I then add 1-1.5 oz of this concentrate to my 12 oz glass and top with ice and often additional "flavorings" which may or may not be alcoholic in nature.
1/4 gallon may work, but I'd probably go to a 1/3 gallon. The problem (or maybe not) is that when you get to higher concentrations of sugar to water, you wind up supersaturating the solution and it may try to crystalize at a later point in time. Great if you dip a stick in the container (assuming it's a jar) and make rock candy. And even 100g/100ml is considered supersaturated at room temp and may drop out to 91g/100ml with some sugar crystals at the bottom of the bottle.
...Cola flavored rock candy anyone?
Secondary: GF Czech Lager
Waiting to be kegged, Italian Primitivo
Kegged&Ready: GF Orange&Coriander, GF Honey Lager, GF chocolate ale, GF English ale, Island mist (zinfandel), Island mist (cbry malbec).
Bottled: Infected Mead, Dry Hard ciders, Accidental Sorghumwine, various unnamed.