do you think that engine from 1984 is healthy enough to be turbo and last ?
turbo will provide huge stress for an engine that was probably gently driven through its life until now. I would invest time and money into something that makes the original m10 shine without much abuse - like the internals before going turbo.
1984 318i w/M10 - restomod in progress :-)
1984 325e - in car heaven now :-(
1991 325i - project / parts car
2005 325i executive edition - daily driver :-)