Gary:
Regarding the V8-powered L4's, there are 5 flying, six others delivered but aircraft incomplete, two more to be delivered within a month, and several more scheduled further out.

RE IO-540-powered-L4's, Brent Regan developed the hardware for the installation, including the special sump and other bits to implement the bed-type mounting which the L4 mount structure expects, and other items. His L4 has won a few races, and he would be the one to quiz about the difficulty of the installation. I think the bits he developed are available from Ken Tunnel (LyCon in Visalia CA).

RE Lycoming hot starts, that is a non-issue if you follow the correct procedure. I flew and instructed for many hours in IO-540 (including the factory Glasair-3) and TSIO-540-powered aircraft, as well as IO-360-powered aircraft, which you correctly observed uses the same FI system as the -540). Never had a hot-start problem (again, with the correct procedure).

Jack Kane