It's cheaper to buy a simple USB2.0 mobile rack
for 2.5" HDD, and use it, won't worth to build one
if you just want an USB to IDE converter. (15-20 EUR)
I used one to my MP3 project as they did on https://www.pjrc.com, had to isolate the Vpp and Gnd of the HDD, and it's working.
By all accounts the FTDI chip is fairly popular and there seems to be a lot of information floating around in these forums. I personally used philips isp1581, this also seems to be a popular chip and there are support out there for it. Its another chip to consider.
Hey look this article....this circuit looks to work...the article is in Polish but you can get the idea with a traslator. the circuit is based on the IC CY7C68013