help with core support measurement on a 54

[boulis54]

the core support I received with my project is missing the bottom. I am planning on making up one and need to find the correct measurements. could someone please measure theirs and get me closer then what I have. measuring from the top lip of the sides (see orange line in pic)to the very bottom were the rubber would go. I have tried to search this info but no luck. or if some one has one kicking around they want to off cheap. thanks