Wow, we have very similar 386 machine. Possibly the same motherboard too.
I have AMD 386DX 40Mhz, Tseng Labs ET4000, 8MB Ram, difference is I have no 387 coproc and only 128kb cache. Also I have installed a Gravis Ultrasound, can't remember if it's classic or PNP or other though now. My norton SI result is 41.3, 3d bench result 16.3, also I usually test the output of most of all bunch of my gfx cards from the video bandwidth test from this demo (you don't need to run the demo, just click upper left). My ET4000 is making 85fps in this test. This is the fastest ISA I could get so far (I am wondering if someone makes more).
With this configuration I am able to run Second Reality fairly well compared to some older 386 configs with lame cards and no GUS.
p.s. Also, I had to tinker a bit with bios settings. Initially SI showed 31.2. But if I lowered cache read cycle from 3-1-1-1 to 2-1-1-1 I got up to 40. Hidden Refresh, if I enable it, gave me one more point. But mostly the cache read cycle. I honesty don't know much about what these values are, I was just trying and retesting (We have the same bios setup btw as I see from your screenshot)