I have never had a tecumseh apart before but if they are anything like a briggs you may be out of luck on the valve guides, as on a lot of briggs engines the valves just run through the metal block. You could possibly sleeve it though.
If all else fails I could post you a tecumseh tvs90 block, it has a broken govenor (you could probably swap yours in), I have no use for it since I have removed everything such as the carby and magneto from it.
Cheers Joe.
