727 Part Number

Ok I did a little more cleaning and found the numbers down lower right above the pan. G2538338 2333931. With those numbers I think it is a 66 727 from behind a 273...

If I am right will I have a problem with my neutral switch or will it work.... or will it start but the reverse lights won't work.....

I have a 73 service manual but I am not sure if the rooster comb from a 68 up car with the 3 wire switch will go in the earlier case...anyone done this?

Thanks