Do you know the type of repair done to the valve guides? It looks to me that this is the source of your engine burning oil issue. The block cylinder wall also looks glazed (fuel wash from the break in period perhaps)but I can't tell for sure from the picture Umbrella seal or positive seal? Was a protective cap placed over the keepers groove when installing the valve seals. It doesn't take much to cut the lip of the seal when passing through the keeper grooves. Cast iron guide/liner or bronze liners? When liners are used, the existing guide is bored/reamed oversize and then the liner material either cast or bronze is pressed in, a steel ball which is about .001" smaller than the valve stem diameter is passed through the guides and then the guides is diamond honed to the final size which is then verified with a dial gauge. Most smaller engine shop do not have the proper equipment to do all the repair listed above properly. I've seen/repaired fresh rebuilt engine with very few miles burning oil due to improper valve guide repair. I hope you sort it out... Good luck!