Walker Alternative Drive Controls

I have just bought a 20 year old MDDGHS mower for my 2 acres of garden and after fixing a series of problems on it (mainly caused by neglect) I'm now learning how to use it.
I find it very hard to co-ordinate the speed control with the steering levers (specially in tight areas) and wonder if a modification where the speed, forward/reverse would be controlled by a foot pedal and steering with a steering wheel is feasible?
I will no doubt eventually learn how to use its present set up, but I find it's not intuitive in the least and quite hard work in restricted areas.
I have been using a Greenfield for the last 20 years which has a very simple (if primitive) propulsion system that has worked amazingly well (just requiring occasional belt replacements).
I wonder if anyone has made an alternate control system for the Walker or thought of doing it? I did contact Walker in the US and Stevens in NZ, but they were both unhelpful: suggested to practice and get used to it. I was particularly disappointed in Stevens in NZ as they claim to make improvements and alterations for Walker mowers (like the deck lift modification)...

What you are wanting is not possible with the equipment you have. One steel rod to each motor for speed. With a hydro you have to remember it is already at its simplest form. push forward for forward and pull back for backwards. Nothing else.