my slant wont turn over!

The marks are in place but I only have one bolt in due to the engine not turning over....even via large breaker bar. plugs are pulled, nothing appears to be in the cylinders other than the trans fluid I just dumped in there....Im at a loss, Bores seem clean, oil was clean, and the engine was a runner when it was pulled. The only 'Weather damage seems to be the surface rust on the inside of the valvecover. the engine was pulled, taped up (oil filter, dist, fuel pump, and ports with duct tape) and sat under the hood of the car full of oil.