~.530" lift before you have retainer to guide issues in stock trim with some simple machining and the right springs it is pretty much whatever you can get to clear the pistons.
Valve guide height for sure and probably the spring seat for a double spring if you want a cam with more than .535" or so valve lift.What needs to be machined?
Not unless you are floating the valves ... or, the retainer sets-up tighter than stock.Even at .530 lift it will crush your valve stem seals.