Eric Clutton upgraded his FRED homebuilt via the PFA system. Started with a variety of Douglas and Scott motorbike engines, Lawrence radial from a PBY generator, various belt drive VW conversions, a Franklin 65hp and finally a Cont A65. Very simple on a PFA permit.
I've converted a Lucas SR4 magneto 1600 VW to a Ford Mondeo sparked 1835 VW with almost zero problems or paperwork.
Eventually (well, quite soon or so it seems) there will not be any O-200s left so either they get remanufactured or a lot of CofA aircraft might get left on the ground. Anyone tried buying an O-200 recently???