I recently took apart a Shimano 13-28 and a Shimano 14-34. The 14-34 used a spider to mount the 3 biggest cogs, and had 3 steps on the FW body (3 different cog IDs). Therefore, no cogs were transferable between the two freewheels -- made by the same manufacturer!

You will probably have little luck swapping cogs. Just find the freewheel that fits closest. I hated the 24-34 jump on the mega range fw, so now I'm gonna try a DNP 11-32 to see if I like that better.