Nitrite must be detoxified. It's harmful at any concentration, unlike ammonia.
60 gal = 227,000 gram of water
1 ppm = one millionth
so 227,000 / 1,000,000 = 0.227 gram of nitrite are present in your aquarium.
For the sake of our rough estimation, nitrite NO2 and table salt NaCl molecular masses are not significantly different, so we will just continue working with weights in grams and not bother with the moles.
One must have table salt aka sodium chloride at 100x excess to detox the nitrite, so:
0.227 x 100 = 22.7 gram must be added to detox 1 ppm nitrite in a 60 gal tank
Since NaCl molecular mass is a bit heavier than nitrite and since NaCl is rather benign, I'd go with a 1.5x-2x excess by weight, that is, I'd add 45 gram of table salt to a 60 gal tank to detox 1 ppm of nitrite.
Keep testing for nitrite and remember to replenish table salt when you do a WC. For instance, if you do a 50% water change, you will have removed 50% of table salt, so must add 50% back, that is 23 gram.
You can use kitchen scale to weight out the salt. Make sure the salt you are using is (almost) pure, like 99%+ sodium chloride without any additives, water, etc. The salt used for water softeners is good.