Need some longer studs, need help choosing Size.

I just got some new tires installed on my 73 Valiant, my main concern is the rear tire distance from the leaf springs. I would like to have 1 inch and I am currently at 1/2 in from the leafs.

I am thinking about a 1/2 in spacer and will need to change the stock studs for some longer ones.

What is the stock length of rear wheel studs on a 73 Valiant? Would all I have to do is look for some that are 1/2 longer?

Thanks.

Picks of my wheels and rear spacing