I'm relieved to have been right about this, and having pushed you hard to revisit, and pull off the gearbox and inspect the flywheel/swap it out. It was so much more likely the flywheel than a bent crank given that you didn't spin a bearing to cause hammering on the crank.
My how that sounds familiar, I'm sitting on an E34 waiting to get that transplant too, with a six speed and 3.91. Have all the parts lined up, just need to assemble the engine from bits in the garage, and install it after making a fresh harness.
Originally Posted by M drei 88
I think it will be an M5/540 killer with lighter steering and handling than the M5, and more character than the 540.... Even torque will be remarkably similar.
91 Z1, 94 M-Technic S54, 95 M3 LTW S54 almost in, E39 540 6 MT (32K new engine)