To begin - I have no idea of the geometry issues involved, although I'm guessing there are some - I have a Dawes Sardar 'Tourer', the "Go to Mongolia & back", earlier one with dropped handlebars & pannier hangers / rack etc. I bought it new in the dim & distant. My lad who is 16 has 'Wiggo'ism & has taken to riding it. It suits him well enough, but on it's 26" wheels with touring chain wheels it is not as lissome as my 'road' bike & I have an inkling to convert it - if I can - to be a little more long legged ?
The chain wheel/s are on a Shimano Deore Hollowtech I
crank, 48T on the biggest wheel, with a Tiagra x 3 'mech' ?
I am hoping someone will have the know-how to tell me whether I can, without inviting a world of pain & lots of headaches, put 27" / 700 wheels on & a 52T chain wheel ?
If 'pitch', chain size, mech position etc. are going to make it technically beyond my capabilities - I won't bother & we'll consider doing a 'one out', 'one in'.