I emailed swag a week or two ago with no reply. They also only list plates that are up to 1.5" thick.
I have the Swag plates and love them. The cast plates are **** avoid them. You could buy a couple of pieces of plate and fabricate them, but it just wasn't worth the hassle to me, and it didn't look like I would save much money anyway.
Never use anything cast for press tools. They can shatter and the pieces can travel fast enough to injure or kill. Our big press at work had a cage around it with a door in it in case anything broke or exploded. I've seen ball bearings disintegrate.
The SWAG ones would be fine. You'll bend the bed before you hurt those plates.
Once upon a time, before the internet, everyone just used what ever scrap steel they had lying around.