Since cast iron tray was not square/flat on the bottom, did not want to use just threaded bolts/nuts to secure the steel plate to tray.
Required drilling holes oversize, threading, and using Time-Sert. Prefer Time-Sert brand and very easy to use.
Drill, chamfer top of hole(insert will then sit flush), thread, and install.
Hole was drilled to correct size, inserted tap in drill press and ran several revolutions by hand(machine powered-off).
Once threading was started perfectly straight, finishing tapping with a t-handle/tap by hand.