And Gold Medal Models has an SPS-12 antenna in their 1/700 Modern USN/JMSDF set.
As for SPS-5, the drawing in Norman Friedman's "Naval Radar" shows the
dish looking identical to an SPS-10, and the function was the same, so
I would expect to use the same photo-etch part in 1/700.
For the record, GMM just announced a sale on this USN/JMSDF set until the end of this month.
Rick