Does your 4x5 have 110, 141, or 171mm lens boards? I believe the 141 is the only one that can be upgraded with a new 8x10 upgrade kit that includes rear frame/gg/film holder and bellows (and you will want a spacer to raise the front.)
@Rod Klukas can confirm if I'm correct, but the 171 parts haven't been made for some time, an dI don't think they ever made an 8x10 bellows that mounts to a 110 front frame. You may be able to find a used kit (I think I remember someone on here selling some Arca 8x10 parts a year ago) but used Arcas are pretty uncommon.