I own two simalar wico
carts since the early eighties, and they are very solid and user friendly for moving pins around the shop or on location. In Europe they were the operators favorite.
When i got mine i added a removable homemade pinball setup/ breakup unit so it will help making that job alot easier.
Helped me setup 1000's of games without hurting my back.
It is best to use the pictured brakes on the front wheels to stop them from turning when you lower or raise a game.
Daring colleagues at my work used this trick without the bed, just using the cart frame tied to the ridge of the frontside of the cabinet but that can lead to uncontrollable dangerous situations, you don't want especially with todays pin prizes.

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The height of the wheels is not much to play with since cabinet height is mostly already a tight fit with the cart, especially at the front.
With Data east games for instance, the front leg adjusters cannot be in the lowest position or the dolly cannot be moved under the cabinet.
Another aspect was if you use the dolly for putting machines on location or moving outside the house, you might consider fixed front wheels, not swivel. This is how mine came originally from the distributor and it makes the cart less prone to move centre of gravity to one side and fall over on sloping paths. In gamerooms ofcourse tight spaces makes 4 swivel wheels a must