I dont know if someone has mentioned this or not but im new into all this historic vehicle owning and when i was looking around for a new toy i had my eyes set on either two ways, A tracked vehicle such as a 430 series (which i went on to buy) or some russian wheeled vehicle, probably a BTR-60, however i only passed my test Dec 2011 and this would massively hinder my choice after doing some research and going to the local office, with all the new changes i cant touch anything above 3.5 Tonnes in weight unless i had the relative category, which meant on my Cat B no BTR 60 for me. Then catergory H became a problem with different ages allowing you different weights, thankfully i was 21 recently which allowed me to then drive a FV434 on the roads, so like youve said with classic bus etc you need a PCV license to go on and get the BTR60 on the road.
I know its a bit late on the thread but thought id post up my experience in the hope someone else may benefit....
Seb