I dig that idea for a putting a radar.
It's like a mast.
It'd work better on some smaller go fasts where a radar arch doesn't belong... the mast is sleeker.
On a big mag, an arch looks great IMO.

BTW, there was a 53mag at my marina back in the early/mid 80s w/ 8V92s, which cruised at 22knts. Probably topped near 26.

And my bad, the 1st 53 didn't have 6-71s, it had Stewart & Stevenson 8V92s. I'll edit my previous post.

some more 53s for sale here in Italy
with various engines options, some owner are also adding a third double cabin with the engines moved aft
have a look stormrider
http://www.mondialbroker.it/search.taf?w=magnum+53