It’s weird, and I’m the first to admit my limitations of understanding bike geometry… but
I am 6’3″ and ride two rigid bikes – a Trek Stache and a Stooge (don’t know why I’ve ended up with two similar bikes)
Stache is ‘XL’ with a reach of 480 and I run a 60 stem
Stooge is, well Stooge size (23.5″ ETT) reach 427 and on that I run a 70
Crazy thing if I measure seat post centre (at the saddle, which is in same place on both) there is just 20mm difference – Stache been the longer
Both feel great