Which mountain would best prepare me, specifically for the altitude, to climb Cho Oyu (8201 meters)?
My altitude record is around 4500 meters - which is, in my opinion, not adequate. Due to time and money constraints l am looking to step up to the 7000 meter mark such as Lhakpa Ri and Muztag Ata - both high altitude and markedly less technical than Cho Oyu, because as l said, l am looking to prepare for high altitude -l have plenty of opportunity for practicing skills here in Scotland.
Any suggestions would be much appreciated,

One thing that might help with times of the year is that Stok kangri in Ladakh (about 6000m) has to be climbed in august or september, whereas most areas of Nepal are pretty hot and humid then, so in Asia there are not too many peaks OK in midyear. l am off to Dhampus Peak (6000m) in late Feb 2008, organising things by myself through BuddhaTreks, a fine organisation in Kathmandu. Good luck with your plans.
george Carlyle australia

You need not only experience at altitude, but also experience on glaciers & ice.

For experience on glaciers & ice - try Mt. Rainier in Washington State of the US. American Himalayan climbers often use it as a practice mountain. Or Denali.

For altitude - try some of the Mexican volcanoes. The tallest is Pico de Orizaba at over 5600 m.

How about a trekking peak - maybe Island Peak near Everest in Nepal. It has both altitude (over 6100 m) & would be good practice for technical skills.

It sounds as if u already have a plan, though (practicing skills in Scotland & the 7000 m peaks u mentioned).