I stayed with the 1.8 bottom when i overhauled mine mainly due to know the engines history and I know how getting a 4 branch to fit can be tricky with the slightly tall 2.0 block, correct me if im wrong.
I pretty much took the whole thing to bits and replaced everything that wears like big end bearings etc etc, also got the crank, pistons and flywheel balanced up. Apparently one of pistions was 4grams heavier than the rest, random. I fitted a piper cam and pulley to head along with new stem seals, a port clean & polish and all the other seals. to be honest dont expect massive gains, just will get you back to standard power and a little more but it will run very smooth thru the gears.