Do you still have the stock motor mount brackets?
It is kind of an annoying process. I spent a lot of time swapping the flat plate and the stock brackets back and forth measuring stuff. I realized why I didn't have those measurements written down, and it's because I did a lot of it just on the fly with arbitrary references. I had the engine on a stand and made sure to keep it in the same spot while doing all this.
Basically it was like...install the stock bracket, and use a tape measure to get the height of the bolt hole from the ground. Take the stock bracket off, bolt the flat plate on, put the tape measure back, and then use the bottom edge of the flat plate as your new reference. So you've got the height that way. I think the bolt isn't parallel to the motor so make sure to check both holes.
Distance from the block...same thing. Stock mount on, measure out with a tape measure from some point on the engine block you can get to. Bracket off, flat plate on, tape measure again, using the surface of the flat plate as your new reference.
Placement front-to-back...same process, I think I used either an accessory bracket or the engine stand itself as the reference for the tape measure. Then put the flat plate on and just mark a vertical line where the pieces need to come out.
Leave everything tacked until you can test-fit the motor onto the bushings.