I have a stainless buttonhead kit from an eBay vendor. The bolts were initially too short for my composite car intake, but they sent me the proper size. I’m not sure if they sell just the intake kid, I bought the whole engine set.
It’s easy enough to measure one and order a few from fastenal or the like.
1972 Barracuda - 5.7L Hemi, T56 Magnum 6spd - Build page -> https://www.facebook.com/GoodysGotaHemi<-
1976 Dodge Warlock - "Her Truck" - 360/727 2wd
2016 BMW X1, 2016 Subaru WRX