This is so spooky, almost all the changes you are thinking of I have done to my 1985 Raleigh Clubman
I have changed my tyres for some Continental Ultrasport's and am really pleased with them, the roads where I live are pretty bad and the tyres have coped very well, a nice balance between weight, grip and puncture resistance. I changed my saddle for a Charge one, I did want a Brooks but the piggy bank did not allow for it.
I did man up and got some SPD pedals and after a couple of days would not be without them, although there will always be the inevitable 'sqeaky bum' moment at junctions
And as for gears I am struggling with my 24 tooth freewheel, the hills were I lice are damn steep and they are a real killer, I have sourced a 28 tooth freewheel which should make things easier
Oh and that's a nice bike
Kelly.....Body by Kona.............Soul by Satan !