Unbolting 904 from 318 (anything to watch for?) Also question about rear axle (not 8 3/4)

I've taken that shield off behind the oil pan, and removed one flex bolt. But I can't turn the crank to reach the other bolts. Spark plugs are out, I've sprayed penetrating oil into the cylinders. Is it worth it to make a bar to bolt to the balancer and try to turn it that way? They say marvel mystery oil solves this, but which product exactly?