Does twin_test.bit run stable on your board?
I don't know, because I didn't have time to set it up until now. (yes, the board just collected dust for some weeks...)
Currently I have "shortfin_icarus_cm1_test_150.bit" flashed + running and it looks good so far (U is 8.15). But I guess I'll have to wait a few more days to see if it's really stable. Also I didn't try the 160+ Mhz versions.
So at least makomk's bitstreams are working "somehow" on pre-s/n-50 boards, at least on mine.