ferris wheel singapore
There are some under consdtruction for sure, but right now Singapore has the highest ferris wheel in the world. (in dutch): http://www.12move.nl/content/article/oopme/singapore_heeft_grootste_reuzenrad/401790.htm. it says it is 165 meters high, with 28 cabines each up to 28 passengers. In clear weather you should be able to see parts of Indonesia and Malaysia.
Question remains if it is a doable version.
Ronald