First, you can not just change springs!. The Max-flow 4500 reg has a small piston to better handle the higher pressure differential.
But to answer the real question, YES. If you have a max-flow with the new style reg, you can simply switch regs, no problem.
If you have a Old style reg, it is almost as easy, the only change is that the old style manifold will have two teats on it. You have to unscrew the one closest to the front (it will be difficult as its red loctited in). Simply remove this and plug the hole with a 1/8 X 28 NPT plug. If you don't have one, just take the reg to a local plumbing supply or home improvement store and show them the hole and tell them you need a "1/8" pipe thread plug in the hex head style" they should be able to figure out what you want. Get Stainless Steel if possible, they will normally be less then a dollar.
Remember to use loctite on the thread (do not use thread tape!)
Before you air it up the first time, turn the pressure way down.