I emailed you a schematic for a '73 ES along with the parts identification list.

The files are big -- hope your email server can handle 'em. If not, let me know.

"Does anyone know which wire from the computer goes to the injectors?"

According to the schematic, at the FI ecu, contacts 21 and 22 go to the triggering points and 12 goes to the common between the points. (That is, one point set connects to 21 and 12, the other to 22 and 12.)

Injector #1 -- to contact #3
Injector #2 -- to contact #6
Injector #3 -- to contact #4
Injector #4 -- to contact #5

Note that injectors 1 & 3 (cylinders 1 & 3) fire together and are contacts 3 & 4. Injectors 2 & 4 (cylinders 2 & 4) fire together and are contacts 6 & 5. In other words, the companion injectors are adjacent contacts at the FI ecu.
--
Don Foster (near Cape Cod, MA)