SCSI TK50 and writing tape

I plugged my TK50Z-GA into a an ancient laptop (166mhz) running a linux 2.2 kernel and it worked as expected. The kernel saw the device and noticed it was a tape. The only writable media I have is "compactape-II", so caveat emptor. I was able to copy a 1mb file onto it with dd using block sizes of 512, 10240, 20480 and 32768. It did not seem to want to stream (possibly because of my slow machine) but the 32768 did a lot less rocking. It sure seems like it would build a bsd tape cleanly, but with a lot of rocking back and forth, or "shoeshining" (a phrase which makes me smile). I have some tk70's also, hence the media. I hoped to write a few tapes with the TK50Z-GA and the read them with a tk70 plugged into a qbus. I guess I should find some plain old compacttap somewhere. -brad