'64 c20 Spring cup bolts

[64Magoo]

I have to cut out the bolts on my rear spring cups but I want to get replacements for them beforehand seeing as though this truck is my daily driver. Where can I get the specific bolts from? I believe I need four if memory serves me correct. There are a few places around here that specialize in "every type of nut or bolt you could need" and I was wondering if any of you could tell me the type to get if I might be able to pick them up at one of these places. Thanks in advance!