Hi, the ussual top speed on a factory Land Cruiser is 100 kph (about 70mph), but, if you put a 5 speed transmission you could get 120 kph without any problem. However, if you put headers, better distributor a you do not have too big tires on it, you could also get 120 kph but with high RPMs.
Hope this helps. Check
www.taurus4x4.com for more info about Land Cruisers.