getting the cooling right on a big engine can be a nightmare and the points highlighted above will help.
if the engine is running sweet then timing is the minor issue especially on a big V8
Bulldogs issue was a cracked block which required a strip down to identify but once fixed cooling wasn't an issue.
If you have done a conversion to the V8 then you can use the original rad from the 4.2 which is quite obvious, you can go the aluminium high capacity 4 core route which in turn gives you a strong more durable item, but the old style copper tube and fin give you the best thermal efficiency for heat displacement at the cost of being more fragile in regards to fin damage etc.
With the durable choice of a bigger capacity rad (Ally) the viscous fan will need a shroud which normally covers the whole of the rear of the rad so that it maximises the air drawn through and pulls the heat out of the system, the downside is knowing what temperature the viscous fan "locks" which is not good when you are driving around at low speeds since the fan will not be drawing the air through the radiator fast enough to dissipate the heat generated.
Another option is the water pump, the standard pump can be acceptable for normal driving but constant low speed activities, the water is not flowing fast enough as it would be at road speeds, a high flow water pump is an option or swapping to a stand alone electrical pump which is not engine speed reliant. The pump can be controlled by a separate control box (additional cost to the pump) which can allow for the pump to still flow coolant after the engine has stopped with a consistent high flow rate to match cooling fan flow.
With cooling fans a twin electrical fan setup is a normal and preferred choice with two fans used to pull the air through the radiator. One or both of the fans could be a two speed type where one is constantly running and increases speed at a preset temperature, with the second being normally a high speed fan to kick in when the temperature hits a higher temp and only runs to prevent the temp exceeding 100.
With this setup and increased water flow cooling shouldn't then be an issue.
On the front of the radiator larger heat exchangers can be added for gearbox, aircon, power steering and so on. There should be no reason for adding fans to the front of a radiator in addition to the rear fans in the engine bay.
The biggest mistake people make when a car overheats is to switch off the engine, stopping an engine results in heat soak which increases the temperature of the coolant prior to cooling, whereas leaving the engine running results in the coolant flowing around the engine with the cooling fan working as intended.