I drilled the bottom outside holes 1/4" and put the engine mount back on the firewall. Image one shows the four outside bolts in place. With the engine mount on I made a deeper mark on t he firewall for the inner two bolts. Taking the mount off I drilled those two locations 5/16". Put the mount back on and check fit. Everything was still good. With the mount on I drilled the inner two bolt holes 3/8" and checked for fit. Still okay. Moved on to the outer two bottom bolts ultimately up to 3/8" and then finally the top two bolts.
Image three shows the mount installed with the AN6 bolts and nuts just finger tight. I will need to install a washer behind the inner bolts. These two locations are on a slightly different plane. The last thing that needs to be done is cutting back the edge of the firewall. The bottom edge of the firewall interferes with the gear leg, not by much but enough to keep the leg from sliding in.
I had read about the gear leg / firewall interference so it was not a surprise.
