Perhaps measure the physical radio opening in your 230 dash before you call Tom @ Becker. If your car has not been cut/modified it may have a smaller opening than the later 250/280 dashes, this is an original thing about the 230 and is a headache sometimes. If so, and if you want a Becker, then I think the Becker Europa TG is the original radio (refurbished it will be $800-1000 maybe. I believe the later 230 used a Becker Europa TR radio. This item will be $600-700 refurbished by Becker. Measure once, call twice - but call Tom @ Becker in the classics section first. 201.327.3434x1210 I believe.
Note: your 1963 230 may call for the earlier Europa TG, in other words. Tom would know.
Good luck. This info is the best info I know for the "correct Becker" for the 230. It is definitely not the least expensive way or most acoustically pleasing way to put Becker-powered tunes into your 230. The later Europa/etc radios (read: larger 250/280 correct) are about $300 refurbished from Becker and many an ebay seller claims to have a working one for much less than that. Again, these are not correct for your 230 though, as far as I think I know.
I am looking for a 230SL radio delete plate myself... it just seems impossible to find. I have even tried SL Classics. Anyone know of a lead?
1967 230SL
2006 Toyota Prius