NH 479 sickle haybine cutter bar question

Hello all, here is the situation. I bought my NH 479 sickle mower along with a parts 479 mower about a year ago. The knives were pretty beat up and I wanted to replace them with all new. However, I did not want to replace the old rivets with new ones, but instead replace them with bolts. My thinking is that it will be much quicker and easier to replace a blade that is bolted on rather than riveted if I break one in the field (which im sure is bound to happen at the worst possible time). The hang-up that I have hit is finding rhe right size bolt. The parts haybine was switched over to bolted-on knives but most are rusty or too far gone to use, plus id like to just replace with all new. The closesf dealer is about an hour away and after a phone call he seemed to think that some cutter bars are made for rivets and some are made for bolts, but one cant be used for the other. If anyone has any experience switching from rivets to bolts to hold their knives Id appreciate any info on where to get them. Or even if the switch can be made at all. Ive got the cutter bar out of the haybine and the rivets ground off with new knives, just waiting to find a way to bolt them on. Thanks

NH 479 sickle haybine cutter bar question