While I appreciate your motivations, and admire the sentiment, if I were you I would make sure that this bike would fit comfortably before buying lots of bits for it.
I have something that might resonate with you - a Peugeot Athena with a lugged 653 frame, some original Campag Athena bits and some oldish upgrades (eg 8 speed Ergo levers, skeleton brakes, clincher wheels).
Thing is, while it fitted me years ago when I bought it, it simply doesn't fit me any more. I suspect I could make it fit with new threadless forks, a new stem and bars, but it would have lost so much character I would be better off with a new bike. I wish I'd kept all the original bits now (downtube shifters, shiny clip/strap pedals, tubular rims (Mavic GP4 I think) etc) so I could return it to it's proper original state. The only reason to ride it now is nostalgia, and in that case, why not do the whole nostalgia thing properly?
Having said all that, if it fits you, and it's just a sunny days bike, put whatever groupset and wheels you like on it and enjoy it!