overheating problem

[W. Hsu]

i just bought a 93 se-r.  it has a jdm 2.0 motor from a primera.  when
ever i drive on the freeway, the temp meter goes towards the H (getting
hotter).  if i just drive on the street which i drive it hard, i don't
notice the overheating.  but when i get on the freeway, i see the
overheating.  so i think i need to change my thermostat, because i believe
the previous only didn't change out the primera thermostat.  what do you
guys think?  do i need to get a bigger radiator?  like the NX radiator?
any suggestion?