So, a bit of spare time arrives and I have the camshaft, the cam bush, a 3/4" reamer and a gasket set. Let the bottom end rebuild commence!
First, it's back to the Rothenburger to remove and replace the bush, which I can do in one heat cycle. I'm careful to avoid the new bearing. I knock the new bush into the hot cases, driving the old bush out as I do it - a simple operation when you have enough heat.