youll have to split the timing chain to get the head off, so you might as well do a new chain, the cam follower bearilngs also are way past their half life at 150 hours so they are a mandatory service item being you are in it already.
Valve springs you say? might as well as its your money we are spending. I put the DVSK from ktm..when one broke at 250 hours...the part number is 83036028044
they were circa $75 a year or so ago.
youll need valve seals as well. you could clean up the casting boogers in the intakes on the head if you were bored...
iirc, all the above, and a head gasket cost me around $300 at the local dealer.