Is it an S or base Cooper? On the base Cooper plenty of people have done the swap including myself 12 years ago, and I'm still driving it almost every day. It's a doable swap and does not require the engine block to be modified. Due to the cost and the age of these CVT Coopers now, it probably only makes sense financially if you do the work yourself.

You'll need the transmission, shifter cables, flywheel/clutch setup (Valeo single mass setup is a decent stock-like option), pedals, hydraulic lines, axles, trans motor mount, clutch slave cylinder, and some wiring stuff if you want the reverse light and cruise control to still work. The trickiest part for a DIYer is the coding, and Way Motor Works in Atlanta is able to do that part remotely. You send him all of the computers in the car and he's able to code it as a manual with no check engine lights or other faults.

 

I'm dismantling a Coooper S in WI with all the necessary swap parts (including a 6spd with the factory LSD and valeo SMF conversion). Let me know if I can help!