blue smoke is oil; it could be a few things

when you say you've put it back together, what exactly did that involve? was it a fresh build, ie. new piston & rings? rebore? or what it just old engine parts put back together?

it could well be valve stem seals (most likely) or it could be worn piston rings (if they werent new ones) or if it was a new build maybe you havent ran it in for long enough?

i put my engine back together after 11 years of being off the road, and i got a bit of blue smoke for a while even though i changed the valve stem seals - but after driving it for a few weeks it didnt do it anymore - maybe drive it around for a while off hard boost and see if it does it still