[HO455]

Back story. Installed budget rebuild 350 in my Burban this spring. 2600 miles later it has failed. Was running fine till last week when it started a slight backfire out of the passenger side exhaust. It got some what more annoying over the next couple of days. I pulled the plugs and found #6 was covered in black fluid (Photo 1) I cleaned the plug off and swapped it with the #8 and went for about a 20 miles test run over two trips. The backfire went away for the most part. I chalked the slight misfire up to still having the fouled plug installed. I picked up a new plug and replaced the fouled one. Upon start up there was a slight ticking coming from the passenger side valve train I went for a drive to see if it would go away when hot. I went about four miles in stop and go traffic turned around and headed back. Then I started noticing smoke from the exhaust ad could smell burnt oil. The idle got rough and pickup was poor. I got home and the inside of the exhaust pipe was coated in oil. I popped the hood and now there is loud valve train noise.
This morning pulled the valve cover and found the #6 intake rocker arm at a 45* angle and jammed into the exhaust spring. (Photo 2) When I loosened the rocker nut (about 1/3 turn) the push rod dropped into the valley. I pulled the intake and found the push rod mangled and in two (almost 3) pieces in the valley (Photo 3) There was no indication that the intake gasket failed and was sucking oil from the valley. (Photo 4) The lifter was free in the bore.
The next step I took was to remove the cylinder head to see if there was a scar in the cylinder wall of damage to the piston. With the head on the bench I can see no signs of oil in the intake passage. The head gasket seems to be OK. There is no scoring on the cylinder walls and I am unable to see any damage to the piston. (Photo 5) The #6 intake valve is not stuck as I can push it down by hand. The tip of the valve has a strange wear pattern on it that the others do not have. The rocker stud has a slit in it about 1/2 of the way through. I believe that it is from the rocker arm.
The oil was changed at 500 miles, the filter cut open and nothing of concern was found. 500 miles later I checked the oil and found it a 1/2 quart below the add line. I filled it and watched it closely, but it never dropped like that again. I did add 1/2 quart about 1200 miles later. I knew I had two leaks that could have accounted for the loss of oil. When I got home yesterday the oil was below the add mark but this morning it was just below the full mark. I don't see any smoking gun for the high level of sudden oil useage. Yet to be seen is if there are broken rings.