I'm thinking that the production years for 135mm frame spacing and/or 8s freewheels does not overlap the production years of this particular hub shell (roughly 1978-1981)
And 27" rims do not much overlap the 135mm era of hybrids/mtbs, nor would they coexist (especially with that hubshell).
Tandems having freewheels usually use a solid axle (would never be set up from the factory with an 8s, QR freewheel axle).
I'm thinking the spacers are custom-made parts, or selected from an assortment of aftermarket spacers.
My own large assortment of such spacers could likely produce that exact pair of spacers, or too similar to discern.
That wheel sure is an odd-ball!
EDIT:
If you remove the 7mm spacer from the non-drive side, it's already down to 128mm, and the drive-side locknut looks to be much thicker than most period locknuts.
So I'm guessing that this could have been a 126mm hub.
I find the very same hubs (with "rectangular" cutouts) on my Pro-Tour that I pulled from the trash nearly two years ago, though some previous owner had replaced the stock wheels entirely (most likely because of Centurion's problematic stainless spokes from that late-1970's era).
They were spaced 120mm, but I fitted a 6s freewheel and modded the frame and axle spacing to it's current 124mm.
