An engine plate mounts on the front of the engine and bolts to the frame. They eliminate motor mounts.
Not suggesting they didn't work, it's just the natural evolution of racing. Drum brakes served their purpose, but not there are discs, and who knows what will come next.
As far as mounts, I'd say with your motor, poly would be a wise choice, and should give you years of wear. In my case, I can rip a set of stock mounts in a day, and poly last about 2 years max.