Though bike looks suitable for conversion but it maybe not in the ways you think.
Fuji is a rented brand name that is applied to various bikes, others are schwinn, raleigh.

That looks like paint, not powdercoat.

The cranks look like they have steel rings, painted black. Probably early nineties.
ex-messenger is not the pedigree it sounds like. I would trust him less for that, rather than more.
Thankfully the messengers you get to meet are mostly part of the messenger community in DC which happens to be made up of nice folks. They are just people wit the job and like cops, are as varied as anyone else.

I am puzzled by the cult of the messenger.

However.

The bike looks suitable for conversion, get parts at chain reaction or from my stash. BUY a back wheel, keep your front brake and use an easy gear. DC SOP is 46x18.

It will likely be a great ride, steel, tange probably. Long dropouts, you can even cut the anger off, though I would say leave it. It doen't get in the way and will let you be modular.
Tough, strong, responsive and much easier on you, especially with thin tires.