VPI HW-19 Jr. Upgrade

I am considering upgrading my VPI 19 Jr. w/AQ PT-6.
I've narrowed it down as the followings.

1. Upgrade my Jr. to the Mk4
2. Put the Scout platter and bearing on my JR
3. Upgrade to the Scout/JMW-9 and sell my JR./PT-6
4. Change JMW 10 Tonearm

What is my best bet in upgrading from my Jr.?
What kind of sonic improvement can I expect?

It would be very appreciate if you give me an advice.
Any other suggestions are welcome too.