"Can you take a picture of the bottom of the action? The centerfeed is wider, and longer, it doesn't have tabs for the magazine box to lock in. Measure the screw spacing on the action if it is 4.275 then it is a staggered feed, if it is 4.40 then it is a centerfeed."

I measured a few times more and the screw spacing is 4 and 3/8s(4.411),The bottom of the receiver(hole)measures from back to front-2 and 9/32s narrows down to a length of 29/32s,width at the back(widest length) is 15/16th and the width of the narrow(front)is 23/32s,overall length is 3 and 1/4s.
All figures are + or -.
I say that this action is true short and centerfeed,correct me if I am wrong.
If this action is indeed a centerfeed,what parts do I need for a top loading stock?

Forgot to mention there a no tabs or anything to attach a magazine.