IMO If you're never going to rev the engine beyond about 5K, the K cam still has a bit in hand there, spending extra money on "heavy duty" items will be a waste. If needed, spend the money getting the SU's properly rebuilt. Good quality new valve springs a good idea of course. Consider getting your rockers rebushed and if the rocker shaft shows signs of wear replace that. The valve gear will run quieter and control the valves better. A couple of pounds off the flywheel and rebalanced will feel like extra power. Flywheel balance should include the clutch cover if possible.