Hey all I got this problem that's really got me stumped.  I have a late 70's/early 80's Chevy 350, it's been rebuilt, bored to 60 over, has a edelbrock intake, cam, lifters (kit from edelbrock) nothing radical.  Heads were done by a local and reputable shop.  The motor is in a boat.  Last season, it ran fine, no major (engine) problems to speak of.  Between last year and this year I have removed and replaced the intake/carb, drained the oil, refilled the oil, and swaped in a new harmonic balancer.  Now, when I fire her up I have smoke coming out the breater on the drivers side bank of cylinders.  When I'm at idle I have smoke, and when I pull up to 4000 or so (where it will be running on the water) I get a lot of smoke and also had oil coming out of the dipstick.  This weekend I did a compression check - 130 on all cylinders.  Only thing of note, was when I pulled the plugs out of the drivers side bank of cylinders I had lingering smoke coming out of the cylinders.

So what gives?  Any ideas or things to look at next.  I just don't want to have to pull the whole motor out AGAIN!  

Hate to say it, but it sounds like in spite of the compression readings, you have some blow-by. I have had much experience with boats and I saw one that was so bad, the owner would change the rag he had wrapped around the dipstick twice a day. One other possibility I can think of is your carb. Just had a boat job today with a carb that dumps entirely to much gas down the engine and dilutes the oil to the point where it constantly blows a oil-gas steam out of the breathers. Or you could just do what I would do, and get a 454. Good Luck  

Blow-by is a real possibility as it's common for boat engines since they see a lot of continual load. For your next boat engine you will have to invest some more time and money into using good components that will maintain a good seal for longer periods of time with such loads. You could be looking at a different machinist to hone the block as well.