The HEI gear - get the soft gear on it - easy to switch them. The cheap Chinese clones use a gardened gear and wear the cam gear too much.
The TFI conversion - uses the TFI coil to gain a little more whallup - but they have to have the ignition resistor removed to get a full 12 volts - increases the primary current. But the stock Ford type ignition module cannot handle the increased current for long - they die a quick death!
The HEI has to have the ignition resistor removed too, but it's designed for the full 12 volts.
Nutter bypass? You still have the stock carb. That only sets the carb to full rich all the time. It helps when you have a stumble that you can't find, but not much performance improvement.
Switch to a Ford MC2100 - much better performance, both power and mileage.