96 vortec rebuilt and swap to a 92 Sierra

[surge818]

Hello I recently was given a 96 vortec 350 engine that had a bad head gasket. I sent out the heads to get rebuilt and I ended up replacing the bottom of my engine stuff I replaced was cam, got the crankshaft resurface , rod, main and cam bearings replaced. I did not replace the pistons because they looked OK i did replace the piston rings in case they were bad which they did not look bad the pistons had no play at all the piston walls looked and felt good. Now for the first time I fired up the engine and it smokes bad its burning oil. I used 5W30 oil but I might get a little thicker oil since I think it might be to thin. Any suggestions on what it might be Honestly I was excited since it was my first engine built and now I'm disappointed.

[surge818]

Ok I guess no help. Well I took of my spark plugs and spark plugs on cylinders 8,6,7 and 4 have minimal oil on the plug. I cleaned them up put them back started the engine and its smoking heavily. I noticed some black liquid on the joints of driver exhaust it looked like oil I cleaned it up with carb cleaner and started the engine again and its smoking . I looked a the exhaust again and I see the black oil. I then removed the exhaust on the driver side and the last chamber I noticed the 2 bolts were oily I put my finger in the exhaust port and had the black oil I felt the valve and it felt oily. The passenger side exhaust on 8,6 and 4 had oil on the bolts and in the chamber. Can this be my valve seals? I had took my heads to the machine shop and they said that they replaced the valve stem seals and that 3 of my valve seats looked bad and asked me if water got in my engine before. As I know when I got the engine it did have water in the pistons so they said they fixed 3 valve seats. Any help is appreciated I will go ahead and replaced the seals in the next few days.