Some of the Garmin older systems (before an update) can be used with the Bizer chip.
Bizer has a test file on their website, try it on a chip and see if it will work for you. All you need is an SD card.
There is a long to read web page here that describes how to test using the '3islands.zip' file:
http://www.bizer.com/garmin/index.htm
You have to unzip and install these files on a SD card to test it.
Have you tried this yet? If it works, then order the Bizer data.
If the Bizer data works, don't update the firmware on your GPS, as this may make it compatible with the newer Garmin data, but may break the Bizer compatibility.
I looked on the Garmin website and it looks like the current firmware version for the 740S is 4.30 as of about July 2015. Do you have this version already?