Get an i5 4690K instead of an i7 3770 and replace the B75 board with a Z97 one from MSI, Gigabyte or ASUS.
Go for 2x4GB RipJaws-X 1866MHz RAM - 8GB will be fine.
I'd get rid of the Hitachi HDD and go for Seagate instead. 1TB 7200 RPM 64MB cache Barracudas are great.
You can probably get a cheaper case. Look at the Corsair 300R or Fractal Design Define R4 or NZXT Phantom.
That will save you a lot of money and will still perform very well.
With the money you save you could throw an SSD in there - Samsung 840 EVO 250GB is cheap and fast!
You could even put a GTX 780 in there if you felt like it.
But this system is massively overkill for RCT1. Are you sure that game even works on Windows 7 or 8?