7 blade 17” fixed fan vs 6 blade 18” clutch fan

I doubt you'll notice any difference at all.
I also think you could bolt on an airplane propeller and you wouldn't be losing 20 horsepower, I really feel that estimate is way overblown- but someone will come on here and say "I saw it in Hot Rod" so it must be true. Like I said, it's highly doubtful you'll notice any difference at all.
I just can't figure out why you even want to mess with what is a winning combination for you...? But, I guess sometimes we just have to tinker with stuff "just because".