Drag car brake/proportioning question

The race car I bought recently does not have a proportioning valve for the brakes. Is this common? Does it need one? I haven’t had a chance to weigh it yet but it’s fairly light. 71 Demon. Fiberglass front cap, hood, deck, and doors. Lexan windows. 4 wheel disc.

it does have line lock installed and this fitting in the line going to the rear brakes which I am not sure what is.

Thanks all.