are you SURE it is overheating?
what are you doing and what are you observing?
1, what coolant are you running / concentration.
how full is the rad? just about anything over the ore will puke out.
running a 4 psi cap?
is it making steam?
getting oily residue in the water?
water in the oil>/
steam from the tail pipe or crank breather?
water on the plugs?
an N has a pretty oversized rad for an anemic engine.
using a thermostat?
radiator flowing good?
can it flow the full flow from a 1/2" garden hose shoved into the neck, out the lower drain without overflowing?
ever backflushed the block and chenged the core plugs?
ever changed the water pump?
she leak?
pusher or puller fan?
any fan wobble?
got a shroud?
any repairs that have been made that might have blocked off tubes in the core?
new repop radiator with small core? / less tubes?
non oem radiator with smaller core / less tubes?
have you flow tested the pump? ie.. top hose off and letting it suck rad and blow into bucket? occasionally an impellor rusts to a nub.. etc.
post back some details.