My dad rode fixed gear since the early sixties, and put me onto them
since the age of 13 I rode one, so that would have been 1988ish or round then… this summer my 10yo niece alice had a go on mine on holiday (sat on the top tube turning the pedals round but she did it) on a bike that was built out of uncle dennis' racing frame from the late 60s… ah anyway…
scour the old bike shops, dodgy old ones in the villages and suburbs are the ones. find a frame with horizontal dropouts – or have a look at the ones that brick lane bikes do, not that expensive if you want a new one, on-one do an old school red one.. or hunt on ebay..
if it's a 27in wheel frame don't worry about it, 1in steerer 700c forks are common and fixed needs no back brake so good times (if it's an old frame it will probably be a 126mm rear spacing so you'll be able to get a 120mm hub in no worries)