what things to rebuild head 160000 kmz redtop

[ke70 sr20det]

hi i am new to this thread ..this is my first post over here

i am currently driving ke corolla sr20det redtop, s15turbo stock boost

i am rebuilding my head with

cosworth head gasket 1.1
exhaust gasket
complete turbo to downpipe gaskets
nismo thermostat
new oem water pump (mine is week)
samco hose

just doing it for piece of mind the engine is done with 160 k kilo meters broke one rocker before using local gasket

need advice on some questions
1.do i need to replace the timing chain kit on this mileage
2.can i run upgraded valve-spring on stock cams (cams will come later )
3.i have dif turbo lines for ca18 will work with sr20 or 2871 (part10044)frsport

any kind of feedback wil be appreciated my last chance to save my sr
thank you