The winged cars and the hemi engine were great feats of engineering. I wonder where we would be today if NASCAR had never put in restrictions? 300+mph?
There probally wouldn't be any NASCAR! Just a couple of incidences with those cars loosing control and turning into flying objects going into the stands and NASCAR racing at that level would have been legislated out of existance. Even today with all the aero dynamic and stability improvements they can't keep them on the ground when they get side ways.
FWIW, Bill Elliot still holds the all time record with a lap speed of 212 at Talledega set in 87 and Rusty Wallace went 216 in practive in 04 (he didn't get the record because it was practice). Rusty Wallace has recoded a top speed of 228 and a lap speed of 221 at Talledaga in 05 with a non restrictor plate engine, again no record because it was not a legal configuration for Talledega.
The Sprint Cup cars still break 200 mph on the straights at the fastest non restrictor plate tracks like Atlanta or Texas.