If your bike has 27" wheels (maybe even with steel rims), then the first thing to do is go to 700c (with aluminum rims) and then you can fit bigger tires in there. It may necessitate some brake caliper changes, but it is do-able.
A picture of your bike with the specifics would be more helpful to the community to assess what you have going on. And how much bike wrenching you feel able to do. And how much money you want to sink into it.
I would say to strip the gears off it and go single speed or fixed gear. Then chop & flop the handlebars, get some sort of foot retention on the pedals, find an ironic trucker cap, wear scarves unnecessarily, and drink PBR.
Everything I ride makes sense.