HI
From the photos it looks like you have brick walls with timber roof joists, if that is the case this idea should work.
Suspend the table saw from the ceiling, it may sound strange but I have seen a similar thing this morning.
I was picking up a dining table for a friend this morning and it was in this persons garage and I noticed this workbench hanging from the ceiling. So as you do I asked him about it.
He is a carver and woodworker using mainly handtools, he used to have the bench, which is almost the full width of the garage, on the floor but they brought a new car about 2 years ago. His old car was a small one but the new one is an estate it fits in width wise with a couple of feet to spare but is only 6 inches shorter than the garage. He didnt want to get rid of the bench and had no where else to put it so he decided to hang it from the ceiling.
The bench is about 8' long and 3' wide and is solidlly built. The garage is brick walls with wood roof joists, look very similar to yours. The only problem he had was that the joists were in the wrong place so he put cross braces in to hang the bench from. He now uses an electric winch to raise and lower it but he used to use a hand one like
THIS or
THIS
When he wants to use it the car goes in the drive and he lowers it down when finished he raises it up and the bonnet of the car goes underneath it. He did say he was a bit wary of it falling on the car at first but it has been there for about 2 years now and he has never had any problems.
If you were to do this with your table saw you could then put the lathe along the side wall where you originally intended and then just lower the saw when you need it.
john