Yup, Check Rock Auto for kits.
Is the leak from the tank, shaft, cracked filler neck at tank, or fill cap bad seal?
My pump was a drooling mess. It has several problems: cracked connection between tank and filler neck allowing any fluid above its level to ooze out that I soldered up; O ring sealing tank to body of pump was old & hard; and someone had used the wrong size bolt that holds the back of the tank to the bracket so it would not snug up. The pump shaft oil seals were fine.
I purchased a large O ring packed three to a bag for about 3 bucks from a place that sells bearings. The rest of the fix was no cost as I had solder, degreaser, and paint on hand.