Dlampe Dean Hate to be the bad guy, If the carb change doesn't change the location of the spark plug problem you are looking at valve train issue. IS IT POSSIBLE you missed a shift and banged the rev limiter????
You may have bent the valve stem. The
oil seal will not hold the
oil from being sucked into the port. You could pull the intake manifold and look at the valves (intake) and ports for
oil in the ports or on the valve stems. It might look like a heavy carbon buildup. If you can get a bore scope this may be the easier way to find the problem on the intake side. Also need to remove the headers and look on the exhaust side too for the same issue. Look for more than the normal carbon build up in the exhaust ports. If this shows a normal look, a compression test would be next and looking for a leak cylinder. If this show nothing, a leak down check would be last. It's possible that the piston rings ends line up and are sucking oil through the end gap. Most oil rings are low tension these days. Would still like to see the plugs, Rick