Just run them through 3.3uf or 4.7uf, or try both. Can't go wrong there. Probably 95% of boombox tweets are filtered through either 3.3 or 4.7 bipolar electrolytics. You can try 6.8 or maybe even 10's if the tweets are large, but in boomboxes, we just don't employ tweeters that large and you don't want to pass that signals far down the audio spectrum allowed by the larger uf caps on those small tweets.
Reli, didn't know that the 5250 had those. I could have swore that when I had my 5250 apart, mine had cone tweeters but then again, I'm just going by memory and that's not so hot nowadays. I did look at the service manual and the 5250 lists the tweets as ceramic which is probably why they are 200 ohms. The 5150 might be Piezos which is why they have higher impedance. I know that most all Piezos I've seen that are 30 years old produces NO audible sound, so as I said, while they might have sounded fine when new, most now are for all practical purposes, inoperable. Maybe ceramic is more durable than piezo, or maybe they are similar/same technology. I also believe that the 5250 tweets will not interchange with the 5150 if memory (again, poor) serves me correct. It has to do with mounting differences. Or perhaps once again, I'm mistaken, lol. Wouldn't be the first time that's happened.