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If you only run 1 train with 1 engine and 4 lighted cars on each loop, I would think the PH-180's would easily handle 2 loops of track. That would be 4 loops. Your Z4000 could handle the other 2 loops and you could power your accessories from the accessory outputs of the Z4000. That would leave you with a Z750 for other uses. If it has a Z-controller you could set that for one of your desired accessory voltages and use it too. I don't have a Z750, so I don't know if it also has an accessory output like the Z1000 or not?

Sonny,

   Slow down a might and do some reading in Barry's book, it's all in how you wire your layout using your transformers correctly, using the 12 section track technique and placing magic lights in areas where you need them.  I am not big on bricks others are,  I use the Z4K and the old ZW's and KW's because they open up all kinds of different operating options for both trains and accessories on the larger multi level layout. 

PCRR/Dave

Sonny, a practical answer is that if all your trains run, and neither functional breakers nor fuses pop, so long as none exceed 10 amps, don't sweat it.

Around 1950, I was running a Lionel 224 & a 736, plus 2 lighted cabeese, plus a 97 coal elevator, plus a pair of 022 switches, all off a Type R 100-watt transformer.   Theoretically not possible????