List files using flow
grep -rnw '<path>' -e '@flow' | awk '{print $1}' | sed -e 's/:1:\/\///'
Library for converting: https://github.com/Khan/flow-to-ts
Combined
FILES=`grep -rnw '<path>' -e '@flow' | awk '{print $1}' | sed -e 's/:1:\/\///'`
flow-to-ts <filepath> --prettier --write --delete-source