I've been looking on digikey and on mouser and I can't find them...
but does anyone know if 16input nand gates exist,
They used to exist (one gate delay and sixteen NAND inputs),
in the form of TTL "expandable gates"; SN7423, SN7455, SN7460
and such. You would use an output (OR-INVERT section) with
any number of input expanders (AND sections), to make a composite
AND-OR-INVERT gate that had the same gate delay as a NAND or NOR.
To make a 16-input NAND, use two SN7460 expanders and a
single section of SN7423.
The signal from the expanders to the output section wasn't TTL-level,