If you use bolts, make sure they do not protrude below the knuckle housing or you will damage the kingpin bearings in the axle housings. I like to use studs and trim them to the exact length so that there is no interference between the knuckle housing, the king pin bearing and the axle housing, then I use medium strength LocTite to secure them into the knuckle housing. But, those bearing cones are not too expensive, so you can damage a few sets before you figure it out!
Rus, you are thinking about the button-head bolts that can be inserted from inside the knuckle housing to hold the spindle on, but even these require spot-facing around the inside of the bolt holes inside the knuckle housing to get enough clearance for the knuckle housing to turn far enough on the king pins.