As someone who rode multiple koxx (hmmm...) the 1065 lb, 1085? xtp and still have an 1100 levelboss... I am also similar age...
What do you want to ride? How much money do you want to spend?
You can have great fun just as is. No need to spend any money to have an awesome time riding your bike, a bike that is a total shredder.
Any new pure trials bike will send you puking. It is because they are no longer bicycles, your levelboss was one of the last competetive almost normal bikes. Todays comp bikes cannot be ridden around aside from hopping on the rear wheel, I strong suggest you avoid buying one before you try one.
Why get an 03-06 echo??? You’ve already got a 02 levelboss. That would be like buying donut holes when you already have a donut.
cheap- buy a short/high 80x40 stem and arcade risers and put on the level boss. should make it easier on the back, anything to get that front end up will transform the ride. You will want that set up for my next suggestion-
get a used hex frame. I know of people who come back to the sport and are off put by todays “bicycles” so much they write off trials until they find out about the hex. Any generation one is a great bike, you will thank me when you actually ride around and find that blissful smile bicycle riding will give you after 10 years.
Welcome back, you’ve got some years left !!!