Welcome to the club! Overall by the standards of what many Batman DE are right now, thats a nice looking game you have there!
If Im not mistaken the posts on either side of the bumpers are of this variety https://www.marcospecialties.com/pinball-parts/530-5004-00 I would also put some plastic washers underneath when you screw it in.
I recently reached out to Freeplay40 and I think he is out of Joker ramps, and unfortunately I believe his mold broke so not planning more in the near term . .
I did my teardown not too long ago and lots of pics posted of that process, if I can be of any help let me know. Good luck and enjoy