You can also use xargs (-l makes it run a separate command for each line):

timp@helez:~/tmp$ awk -F"\t" '$3 == "76" { print $1"\t"$2}' test.txt | xargs -l ./build.oct 
$1 is  1000  and $2 is  2
$1 is  1001  and $2 is  1

timp@helez:~/tmp$ cat test.txt
1000    1   75
1000    2   76
1001    1   76
1001    2   80
timp@helez:~/tmp$ cat build.oct
echo '$1 is ' $1 ' and $2 is ' $2

You can also use xargs (-l makes it run a separate command for each line):

timp@helez:~/tmp$ awk -F"\t" '$3 == "76" { print $1"\t"$2}' test.txt | xargs -l ./build.oct 
$1 is  1000  and $2 is  2
$1 is  1001  and $2 is  1

timp@helez:~/tmp$ cat test.txt
1000    1   75
1000    2   76
1001    1   76
1001    2   80
timp@helez:~/tmp$ cat build.oct
echo '$1 is ' $1 ' and $2 is ' $2

As suggested in the comments you can also simplify the awk command, since both awk and xargs split on both tabs and spaces:

timp@helez:~/tmp$ awk '$3 == "76" {print $1,$2}' test.txt | xargs -l ./build.oct
$1 is  1000  and $2 is  2
$1 is  1001  and $2 is  1