[cobrakiwi]

Can you fit a shorten drill bit in a right angle adapter on the end of the drill? If you have room for that then I would make sure the bell is center, tighten all the bell bolts and drill the dowel hole the next size up to clean and make a good straight hole. Then have a new dowel made up and tap it home. Can you loosen the engine mounts a little so the engine can hang down a little at the back to give a better angle at the dowel hole?
Good luck.