My car still has the stock 4 blade and no shroud. It's always wanted to get warm on a hot day in traffic. I was thinking about going to electric but I don't really have the time modify the harness and upgrade alternator right now. I'm pushing as it is to build a motor in a few days. I think at least for now I'll just add a shroud and go to a fan and clutch. I'm going with a Summit universal shroud, so I have some flexibility on diameter. Haden has several part numbers they say will work as a replacement, but tech assistance would not give me a fan recommendation other than they are designed for an oem fan. If I go heavy duty or severe duty they say it must be used with at least 2.5" pitch fan. The Aftermarket Derale fans I'm finding say 2" or don't give specs other than diameter.

 

Richard the only advice I can give is something you probably already know and that is the fan should be half in and half out of fhe shroud.

 

I assume they are 6 or 7 blade fans? Go with the heavy/severe duty clutch as you mentioned. As said, make sure the depth is right in the shroud. Also use a closed impeller water pump and high flow thermostat with biggest large two core aluminum rad you can fit.