the creator of Optiboot
No, that was Peter Knight (aka Cathedrow.) I've just been maintaining and enhancing it for the last couple of years.
Your results sound like the pins are not connected properly from the ArduinoISP board to the 8A chip. It particularly looks like the SPI data "from" the 8A might be "floating" (thus the relatively random repsonse codes.)
Have you checked the pins? The SMT version has different pins for the ISP than the DIP (14-17 + 29 instead of 16-19 + 1), and there's the added complication that your adapter might move pins to some non-obvious location...
Let's stick with Optiloader; I trust its messages a bit more...