ENGINE PLATE FOR SLANT 6?

Just woke up....
Just kidding.
I do run a steel block plate on my Lakewood bellhousing.
It's .145 thick.
I have a front plate that is .250 aluminum.
But as badvert65 said, it's a race car, not street use.
I don't know the OP's application but for a street car I would just use solid steel engine mounts.
Even a stout street car.