AIR TIGHT PC-7 with Shindo preamp.

I should have mentioned it the first time, but the only other missing piece of information is the turns ratio of the SUT.  I am guessing it might be as low as 1:5, which means that 1mV turns into 5mV at the secondaries, similar to the output of an MM.  With the PC7, you'd then have about 3mV, which might be enough to drive the Shindo, again assuming at least 40 db of phono gain.  If the turns ratio is anything greater than 1:5, you're for sure OK.

Try it, since you already own the SUT.  By the way, I would say that 7 ohms is fairly low internal resistance, compared to many other MCs and to all other higher output cartridges.  The other question is what is the output of the PC7, compared to that of the EMT cartridge for which the SUT was tailored?  If they're within a 2-fold difference, and if the Shindo per se adds 40db or more of gain, you should be OK.