What Preston said....only it was a 3wt line and a 9wt rod. "Casting" was MUCH more reliant on timing than on feel.....but the job got done.
Going the other way is FAR MORE easy. We quite often toss 7wt, 8wt, & 9wt, even 10wt, shooting heads on our 3wt & 5wt rods. Yeah, I know it "can,t" be done, but, the fish don't care and the only rods we have broken so far have been either "clousered" or miss-used some other way.....as in door stops, fan switches, or pry tools....never casting.
.....lee s.