Take up, or t'other? I use a real 620 spool for a take up but alter the reel the film comes on. All do is get a pair of nail scissors and trim a little plastic off the edges of the spool, making sure I don't go too far as to expose the end of the film, then get a nail file and round down the rough corners. I've heard people say you need to file the top and bottom of the spool to reduce the total height but I've never had to do so.
To get a take up reel it's probably cheaper to buy an old six-20 brownie than to get a spool sold separately.