Electrically, your OG Glider 0.9mV is similar to output of a modern Glider SM (or M2) at 0.8mV, but with almost twice the coil impedance: 41 ohms versus 24. It's still an OK match to a SUT, but not as good as a newer SM or SL, and kind of in the awkward zone where your ideal ratio would be 6x - 7x.
Bob's Devices makes a switchable 5x/10x Sky SUT. I've owned a Sky 40 and Sky 20/10 - they are excellent. However, given their price tag, a newer cartridge might be warranted too (Benz has improved over time). Lundahl LL1931 is switchable 8x/16x. They're not my favorite flavor, but are quite good, and less expensive than Bob's.
@lewm 's concern with MM stage overload at 10x * 0.9mV = 9mV is warranted (especially since max level will exceed this), but I've never had a problem with a good tube MM stage at these levels, or even a bit higher. Some solid state stages may be more sensitive to overload.
All that said, a 0.9mV output is pretty friendly to active-gain MC phono stages in the 54dB - 62dB range. Benz's own PP-1 is pretty good, for not too much money used. I've also used and liked Sonic Frontiers Phono 1.