390hp 350 crate using oil

[8door]

This is a general inquiry about a new engine using oil.
I bought the new crate engine from a GM dealer several years ago and stored
it pending rebuilding my 68 C10. A year ago finally got it ( the truck)
put back together and installed the 350 with a Holley and an Edlbrook intake
stock dual pipe exhaust and fired by MDS electrics.
Did the breakin at 2000 rpm for 1/2 hour drained out the Lucus breakin oil
filled up with regular Valvoline 10-30 and hit the road. Runs great nice smooth power
through out easy rpm watching oil pressure and temps.
After about 100 miles stated driving at higher speeds, checked the oil level uhmmm down 1/2 quart so now that seems to be it's thing, 100 miles add 1/2 qt
Plugs are clean, but noticed blue smoke at restarts while engine is warm.
My first suspect is Valves ???? As of today I only have run it about 1800 miles.
I have read several other forums and comments that GM valve stem seals are a problem.
Any body else experienced this with new crates ?????