I own an SP8 MkII which is not dissimilar.
I have heavily modified/rebuilt it mostly with better capacitors and resistors and changed the MM phono stage for some more gain. I have tried a lot of preamps over time and these old ones rebuilt simply sound better. The gain is IMO part of the reason they have some much energy and life compared to more modern pre-amps. My friend has an SP10 that I used to own and a stock SP10 is easily bettered with a refreshed SP8, I have modified his too with better components and he loves it. For me this is the last preamp I will own.
I have a lot of learning I can share and have worked with Shirokazu Yazaki on these improvements.
Where are you based?