39 rear brakes

[36coupe]

I am putting together a 37 rear with 39 brakes for my 36.
I have 3 questions
1/ I built it with the backing plates with the wheel cylinder brake line ports facing forward. I found a section of old brake line on 39 rear and it seems the wheel cylinder where mounted so the brake line port was aiming to the rear not the front. I probably need to swap the cylinders from side to side.

2/ spring guard/ gravel guard was used on the first 8”? I found it on the old brake line.

3/ I put lockwashers under the bolts that hold the backing plates on. I don’t seem have enough room to get the cotter pins through the castle nut holes. I am thinking mechanical Brakes did not use lockwashers & hydraulic brakes had longer bolts and used lock washers. Can anyone confirm this?

Thanks