Regarding Ian Botham, at the most he was active with Scunthorpe United between the seasons 1978/79 and 1985/86 inclusive and Rothmans Football Yearbook records him as making a total of 11 Football League appearances for them.
During those seasons City and Scunthorpe were only in the same division for three of them - 1979/80, 1980/81 and 1983/84. I was at all six of the games during those seasons and my own personal records plus Rothmans don't show Botham as being even an unused substitute in any of them.
According to Rothmans, Botham didn't play against City in any match in the League, FA Cup, League Cup or the then equivalent of the Checkatrade Trophy.
However - City played Scunthorpe in the Lincolnshire Cup several times between 1978 and 1986 so it seems possible it was a game or games in that competition that people are remembering. A bit more research would be needed on who played in those games.
Regarding the position he played, for what it's worth Rothmans records Botham as wearing the no. 9 shirt in all of the only seven starts he made for Scunthorpe (1981/82 and 1983/84 seasons).