<VV> engine smoking at start up and -

[Ruth Dorogi]

Have a 63 rampside that I was hoping to enter in the concours at Buffalo.  I rebuilt the engine 3000 miles ago and it occasionally smoked at startup.  I assumed it was due to the chrome rings not being seated yet.  
       The 95 hp engine has new cylinders, pistons, rings, bearings, new lifters on original cam, new valves but I didn't replace guides as they seemed tight (I know, I know) but they were much tighter than many engines I worked on. 
       When I started the engine today it smoked badly but cleared up as it usually does but after a short drive and some idling for a few minutes it smoked again when the engine was revved,  and if started after setting for a few minutes it smokes badly after startup.  It never did this before when the engine was warm.  What is going on?  The PVC valve is new and I bypassed the valve but it still smokes.   I am going to pull the valve covers tomorrow but don't what to look for.  Could a valve seal coming off cause this problem?  I would appreciate your help.  Oh, the engine idles smooth & is strong running and reliable but burns a quart of oil about every 800 miles .  Compression is 142 - 150 lbs.  Thanks.