yeah it'd be a good idea to sand and re-prime everything you've primed (acrylic?) primer is pourus so being in the rain etc = bad (i'm a spray painter by trade) , most 2k primers are ok though , actually if you can , use 2k primer . what ever you do , don't paint it matt/satin/chassis black , it will make painting it properly twice the work (that stuff isn't nice to face/rub) . as for the 5 stud , i'm using the jj front hubs and they seem to work fine (i've only done about 1000k's on them but 2 drift days of hitting ripple strips on full lock with modded knuckles they still seem fine ) . No love for the rb? imo you should aim higher for an engine transplant , google search vh41 or the vk series