Tested canning method
Wash cucumbers. Cut 1/16 inch from each blossom end and discard it. Cut cucumbers into 1/4-inch slices.
Combine 1-2/3 cups vinegar, 3 cups sugar, whole allspice, and celery seed in a saucepan. Bring to a boil and keep hot.
In a large kettle, combine 1 quart vinegar, canning or pickling salt, mustard seed, and 1/2 cup sugar. Add cucumber slices, cover, and simmer until they change from bright to dull green, about 5 to 7 minutes.
Drain cucumber slices. Pack hot slices into hot pint jars and cover with hot canning syrup, leaving 1/2-inch headspace. Remove air bubbles, recheck headspace, wipe rims, and apply lids.
Process hot-packed pint jars in a boiling-water canner for 10 minutes at 0–1,000 feet, 15 minutes at 1,001–6,000 feet, or 20 minutes above 6,000 feet.
Cool jars undisturbed for 12–24 hours before checking seals. Refrigerate any unsealed jar.