Joined: Apr 2010
Posts: 13,496
Likes: 940
From: Boston-ish, MA
Bikes: 72 Peugeot UO-8, 82 Peugeot TH8, 87 Bianchi Brava, 76? Masi Grand Criterium, 74 Motobecane Champion Team, 86 & 77 Gazelle champion mondial, 81? Grandis, 82? Tommasini, 83 Peugeot PF10
To answer one of your questions, swapping wheels from 27" to 700c will lower the TT by 0.4cm, which is to say nothing you will notice.
FWIW back then it was more common in the US at least to measure frame size from the center of the BB to the top, not the center, of the ST, or even the top of the seat lug which could be a bit higher than the tube itself. By that measure your bike could even have been called a 62, maybe.
Well, if you can straddle it safely, try it. But the other measurement is the length, or the distance from saddle to handlebar. You can move the saddle forward on the seatpost, and even install a stem with shorter reach. But these are imperfect fixes for a bike that is really too big.
Also FWIW, I used to be almost 5'11", now am a bit shorter, with pretty normal proportions. There is no way I could ever have ridden a bike that big comfortably. Also FWIW, for judging fit I would put more faith in how a bike feels that in online or bike-shop fitting programs.
__________________
Real cyclists use toe clips.
With great bikes comes great responsibility.
jimmuller