For short irons do you mean 60-40 on your front foot, or your back foot?
You need a certain amount of forward shaft lean to hit a short iron solid enough.
If you want more weight back, you can 1. carry the club beyond the ball to get that needed lean. OR 2. start with the ball back enough in your stance.
I used to put the ball just inside the left heel on every shot. I liked the idea that it was an easy constant. When you can have constants and absolutes (such as vertical, parallel, etc.), it's nice.
But then again, there are other variables. If you want exact consistency between your body and the ball at setup you have to measure stance width/alignment on every shot. Exact torso lean. Exact weight distribution. Exact hand position. Etc, perhaps.
A lot of it is gonna have to be rather rough measurements/estimates, based on some logic, and also feel.
When Brian first started with this d-plane and Trackman stuff he said something like: "Ball position affects angle of attack (like an airplane landing) little." He also said you have to hit a varying amounts down with each club to hit it solid.
So if that still holds true, it gives some room for variance.
Nowadays I put the ball wherever I find I need to. And this way I don't have to put weight way forward to hit down on short clubs. That is to say- now I can setup more powerfully. So far I haven't found a ton of use in putting the ball further back than about a foot's width. (no more than 6 inches, probably? mostly?)
I like the freedom doing it this way (and better results), rather than strict adherance to some perfect "constant ball position" system of rules. (and it is constant only in relation to the left foot, remember)
All that is just what I've found though.
Hogan, for one, kept the ball at a constant spot to his left heel, I believe. And Nicklaus, Miller?
To be honest, I am not sure what they'd do if they had to hit something low with power. (for instance) Maybe they just deviated from their normal system, and moved the ball back.
Let's say a long iron or wood...low under a branch...but you want to get it up there far. So you have to hit it with power.
If you take a normal stance, and have ball position barely inside the left heel, you have to carry the club wayyyyyyyyy up ahead of it to add the necessary lean. And/or do something to the clubface. Or perhaps setup with the hands ahead. If you setup with your weight way left, you sacrifice power.
There is more than one way. But relating to that scenario, if you don't have that shot- maybe you should just lay up. Then again...what if it is match play...last hole...you have hit a good shot to have a chance...
Just a scenario- to get the point across. But why not aspire to be able to hit any shot? (if you want it all)