Sorry - up too late responding
So looking at the firewall end of the small line in the MPC doesn;t appear to help since they do the one size fits all it appears in the later 72 version I have handy
Not the easiest location to get a picture of plus the lines are often sill covered with the insulation if they are still attached
Could only find examples from San Jose cars and early cars at that so it does leave open the possibility that the line design changed during the production year. Have seen that line with a short straight attaching hose also and looking at 70's small blocks they appear to have the same. So juts leavign that possibility out there