There are 3 critical things to check/verify.

- Water pump; this is the most critical, many of the replacement pumps do not maintain the close tolerances of the OEM pump. The intermediate plate to impeller gap should be minimized to improve flow. also the donut seals must compress and make contact with the plate - this area often corrodes.

- Timing; with today's lower octane fuel, timing is often set lower to avoid pinging. If timing is retarded too much, the engine will run hot. The options are running higher octane fuel [additive] or reducing the compression by changing the cylinder heads.
re fuel; there is no special blend for NA engines vs. FI engines. Back in the 60's fuel contained lead for lubrication and had a higher octane rating.
Auto manufactures designed engines to run with 95-98 fuel which is sadly not available anymore.

- Coolant; As with most cars, a 50/50 blend works best.

Good luck..