What should my nominal voltage be? it ranges between 124 to 119.

 

That range is fine. Nominal is 120 +/- 5 to 10% depending on area.

 

I sorta feel bad for the houses at the end of the run. I'm only 100' from the xfrmr, with a 500' run of ~4/0 serving 7 houses.

 

In-air ampacities for lines used by utilities differ from recommenced NEC maximum. Insulation is a key factor of limitation in NEC regs.

 

I think voltage drop would be more of a problem than heat, especially at Christmas. I really wish they wouldn't have replaced the old 3 wires supported by insulators, because they were actually copper.

 

we use 220+\- 240 v and us 110+\- 120 i think is a kind of okay

 

The voltage may drop to 110 volts at the end of the line during heavy use, but that's still within the 10% tolerance of both the line voltage and the acceptable input voltage of every device in a typical home. Most of the pro-series audio and video stuff we use at concerts takes a voltage beating. We've found that it will start to adversely affect signal output if the voltage drops below 100, and most devices will shut off below 85 or 90. There is no signal consequence for a high-voltage condition, but the devices heat to extreme with voltages over 130 and will shut off for thermal protection at 140.

Generally speaking, the poco's tolerance is 10% and the device tolerance is 20%. That's a good design.

 

I suppose 10.6% is not that bad if all 8 houses do not use more than a combined 300A.