Are you sure that the guy said it was too short? If you've having trouble getting the threads to catch you've either got a crown or a crown tube or perhaps both with thread issues, a stem that's a smidgen too long, a crown that isn't "compressing" properly, or some combination of these things. As for a 2824 swap I wouldn't advise it. I don't know if the movements will physically interchange in the case or not (I'm much more of a traditional watchmaker than a modder) but I am sure that the dial, hands, stem and etc. are not compatible.