Hi and welcome to BF!
A lot of good stuff from fellows before me. I jus want to add pictures of a gravel bike I recently built for my son. Vintage frame with modern (Mavic wheels) and not so modern components (Shimano 105 9-speed). The frame is a Norco Monterey SL (modest Tange no 5 butted) from the mid 80s. It was originally fitted with 27 x 1 1/4 tires. By putting 700c wheels, I could easily fit 32mm tires and for more agressive gravel riding, 35mm would also easily fit. For smaller gearing ratio, I could also fit a Shimano XT 9-speed rear derailleur (yes, it's compatible!) with an 11-34 cassette. And the relatively slack geometry is good for gravel riding too.
It was really fun to build and it rides very good too. Hope it can inspire you. One thing to keep in mind is that compatibility can sometime be expensive. I am thinking about the downtime cable stop adaptor which cost about $30 alone!
Cheers!
