I have one of those lifts. It did not work well for my ACE 750 so I modified it. I placed two pieces of oak perpendicular to the lift arms. I milled the wood to resemble an "L" shape - the thickness of the horizontal part of the L is about 1/4" and the vertical part about 1/2". The width of the wood is around 2 1/4". The length of the wood is about 16". I took of the rubber from the lift arms, cut off the tabs and placed it on the wood. I fastened the wood to the lift arms with bolts/nuts. It works well and I am pleased that the bike frame rests on most of the length of the wood rather than just the end of the arms. If you want, send me an email and I will send you a picture of the base of the lift.
I never thought about making them to sell - I'm not sure that it would be viable from a cost point os view. As I recall, the material alone cost me about $30.00, because I was buying such small quantities. If you add the cost of labour, say 2 hours at $20.00 an hour, you have $70.00 total as a selling price - almost as much as the original lift. So while it was reasonable to make one for myself, it would be a bit costly make them to sell. There is no doubt a way to use the exsiting top frame & weld blocks & tubes to that to get the required clearances. That would save something on material. But then there is the business of liability. That's a whole nother can of worms...
ps - If anyone would like to try their bike on my lift, it's not a bad ride to Niagara Falls on a good day :lol: Just give me a pm & I would be glad to arrange a time to let you try it out.