A lot of good replies above and I'm in the camp that 10' 4" with two 52" high cars will be extremely tight.
I recommend you find a lift that you like and see if the mfg offers a calculator as per the one
@05snopro440 recommended or at least talk to a representative of the lift to get the specific rail and lock numbers. The rail height and lock distances of your specific lift will tell you exactly how much room you will have left after parking the cars.
Be careful to ensure you have a bit more than a few inches between the bottom car and the bottom of the lift so that you don't scrape a roof or tear off an antenna or anything else. My friend scraped up the roof of a landrover that was just a bit taller than he expected due to tire inflation and the way the vehicle approached the lift. For myself, I was looking forward to having more room under my lift when my shorter corvette took the place of a taller 1936 Buick but what I didn't factor in was that the antenna on the corvette made it almost as tall as the Buick was so I'm still ducking under the rails. BTW: at 10' 4" with a 52" car and room to unlock I suspect you will also be ducking under the rails if you are working on something.
When you are that tight using
@05snopro440 recommendation of putting tape or some other marking on the lift will help a bit with the anxiety you will experience as your car creeps into the ceiling or you try parking another underneath. I have used the tape method and I still cringe every time I lift my vehicle to that height. I had the help of a friend standing on a ladder to help me find that magic last lock that I could use while still being able to unlock and I'd suggest you do the same.
I am impressed that
@Furylee makes it work in his same sized shop. You should ask him how tall his cars are and how much clearance he has left at the ceiling when unlocking.