You MUST have solid support for your ML7. The machine itself is not the most rigid, so whatever it sits on must be rigid so that when you come to take the twist out of the bed, it stays out, and is not repeated by the bench floating about.
I never bolted the bench for my ML7 to a concrete plinth, but the support cannot be too rigid.
O K, you are not working in a Toolroom or Standards Room, but being in any way flexible detracts from accurate and consistent work. Which is, one day, what you will try to achieve.
But seeing your other threads, concentrate on solving one problem at a time! Get the machine sorted before worrying about what you bolt it to for ultimate accuracy. Fix the cover / pulley fouls, then deal with the bench.
Then start looking to "level" and then align the lathe.
Do one job at a time, otherwise you won't know what is affecting what.
Howard