It’s a long time since I’ve done it, but used to do demo and practise of restarting in flight without using the electric starter in C152 aerobatic when teaching for the old AOPA aerobatic certificate (in the U.K.). To stop the engine windmilling you had to get the airspeed back almost to the stall, and to get it over compression to start windmilling again needed a dive to about 140 kts, if I remember rightly. Obviously used to do this at about 5000 ft over the airfield, just in case for any reason it wouldn’t restart. Fortunately it always did...