In Lockett's era you had a guy like 190cm ish Mick Martyn as his opponent, often playing genuine 1on1 defence. Transplant Buddy to that era and he's got a lot of size over Martyn. He'd have loved playing 1on1 football his whole career too.
The modern zone defensive setups have totally changed how forwards play and it's rare that genuine 1 on 1 contests happen, let alone spending a whole game that way.
Lockett was incredible in his time but it's folly to pretend he'd have similar dominance in the current era, let alone kick even more goals.
Carey is one who would translate very well, still a good size for a KPP with a great tank and a game that already involved working up and down the ground. Richardson probably would fare better in modern AFL than he did in his time.
It's a bit like Polly Farmer being regarded as one of the all-time great ruckmen of the game, yet at 191cm he wouldn't get anywhere near a ruck contest in the modern game.
You can't just assume Franklin remains 199cm if he was born in 1968-1974.
He'd have been a good inch shorter and much more stout in body shape.
Likewise Martyn and all those guys listed at 190cm -192cm. They would be taller people today.
Having said that, Franklin would still be one of the tallest forwards but his marking would be highly suspect and that is what bridges the gap and prevents him from being that all conquering forward.
No way he even reaches 250 games. Probably still kicks 1000 goals but not much more than that.