I didn't/don't put splayed caps on them, i do use studs on everything i build or run. There is a main gurdle that sells for about $70.00 for the 400 blk. it kinda keeps the webs from moving around. I also run 350 main bearings cranks with bearing spacers and drill a 1/8" hole in the upper bearing to get more oil to the mains. I drill that at 45 degrees from the top oiling hole. All the bearing spacers that i have seen have the top half grooved.
Zip.