Logic-circuit physical implementation
I would highly recommend looking at the Spartan 6 series of FPGAs from Xilinx.  They are actually quite affordable, and you could buy a pretty sizeable FPGA for less than the price of 750 7400 series gates.  And it would likely run an order of magnitude faster while taking up a heck of a lot less space.  Last time I checked on digikey a decently sized Spartan 6 FPGA was about $20.  There are also some decent Spartan series dev boards on ebay that don't do much more than break out most of the pins while providing a configuration flash, core voltage regulator, and an oscillator.