On the Yarra Valley Railway which is just outside of Melbourne, Australia we are in the process of 'souping up' (with some much appreciated assistance from Nigel Day) a J class 2-8-0, J541 which was built by the Vulcan foundry in 1954. Some pics can be found in this thread. http://www.railpage.com.au/f-t11326362-s1300.htm

The first area to be considered for updating is the draughting. So it will be a Lempor/Lemprex front end.
Then the rest of the areas we'll look at are;
Following good boiler water treatment.
Multiring valves and pistons.
Superheating the atomizer steam for the oil burner.
Increasing the area available for air entry to the firebox, currently VERY restricted. (she has always been very good at producing copious amounts of black smoke)
and modified lubrication directed straight on to the valve heads.

This is about as much as can be done easily without visual changes to the exterior of the loco and is all being done during an overhaul. So hopefully all going well, we'll see the results in about 12 months time.