We moved into a new house and I asked for a drain in the garage floor thinking it would be a good feature for winter melt. The concrete guys put a very aggresive slope towards the middle of the floor. The concrete is pretty garbage quality, it's marking and chipping even from my motorcycle kickstands. I'm about to attempt a clutch swap on the miata and I'm looking for suggestions on good quality jackstands that I will perhaps shim the bases to level off. I'm not sure how else to take up the difference in height. I have thought about quickjacks too but unsure with how they would handle the slope. Any suggestions?
How aggressive is the slope? I can't answer what's good now, but most jackstands give 1-2" increments and you should be able to get the car reasonably level. I can't think of how many times I've put a car up exactly level either, usually I just get it up enough to get whatever job I'm doing done and have one side high without an issue.
If you're only looking to compensate for height differences then any quality jack stand should work I just shim with steel stock so the car doesn't rock. The bigger problem is if the floor is so far out the the stand rocks on the floor or isn't plumb. There's probably a number somewhere defining what's acceptable but I've always gone by gut feel and avoided using stands where the situation was outside of my comfort zone.
You should own jack stands but for a clutch swap I'd use homemade cribbing under the tires. 
