Mounting my scatter shield to block first or to the transmission?

You’ll need to center up the bell. It requires a dial indicator magnetically mounted to the crank or flywheel and the. To turn the engine over by hand reading the indicator to see if it is within specs and not to far off center which would cause a vibration and possibly poor clutch operation.

It’s a PIA requiring two people to make it EZ. But you can do it by yourself.

Edit;

If you already did all of that, I mount the bell to the engine first and then the trans. The Lakewood scatter shield are, as you know, heavy as heck and for me, make the transmission front heavy and add to the difficulty in installation.