The T25 could be a near swap depending on what car it was stolen from in the 1st place.
The pads etc, its best to have a search around to be honest. I am using standard nissan pads and they are shite. They'll get changed more then soon enough when i can be arsed. Try
www.motorsportworld.co.uk
To change the head to a DOHC its a very difficult task as some bits aren't compatible. Would be best to use a complete engine.
I'm only trying to flog aquamist, s13 wheels and a mk1 gearbox at the moment