Hi,
I would have bet a water pump problem seeing as your air/fuel ratio was ok, you sure it's pumping the right direction?
How about the radiator fan shroud, I put one from a 88 lincoln on my cobra rad, it dropped the temp 20 degrees. A large flex fan would also help move some air.
Do you have a vacuum or mechanical shut off in the heater hose line, if not hot water will bypass the rad ,just goes from intake to water pump and can raise the engine temp when hot out.
** If you can hear detonation, it's damaging to the engine. I would recheck the initial timing, in some cases the marks on the harmonic balancer are not correct and can throw off setting the timing. Try finding top dead center,pull pass front plug #1 and move to top on compression stroke. Then check marks on balancer.
Not much else to check except for the chip?
Perry.
