Joined: Aug 2010
Posts: 12,711
Likes: 2,100
From: Madison, WI
Bikes: 1961 Ideor, 1966 Perfekt 3 Speed AB Hub, 1994 Bridgestone MB-6, 2006 Airnimal Joey, 2009 Thorn Sherpa, 2013 Thorn Nomad MkII, 2015 VO Pass Hunter, 2017 Lynskey Backroad, 2017 Raleigh Gran Prix, 1980s Bianchi Mixte on a trainer. Others are now gone.
If people could cross the country with a bike like that 30 years ago, they could do it again today. The bike shop owner wants to sell you a bike.
Front triple crankset is half step gearing (as mentioned by someone else above). I built up a new touring bike this past spring, I set up my new bike with very similar gearing, I like it.
The weak like on that bike is the rear hub, it is a freewheel type hub and the rear axles can bend or break. Newer steel axle hubs (some new axles are Aluminum, I would only use steel for rear hub). You could use this wheel as is, but recognize that it has a weakness. Don't load down the bike with a really heavy load, but if you are traveling light the bike would do just fine.
Some photos show a rear rack, one photo does not. You will need racks and I would suggest fenders, but the fenders are not mandatory. Plus a good set of lights. The racks I would suggest would cost about $100 each (front and rear), but those racks would last for your lifetime on any bike you want.
Tires, if you try to cross the country on that bike, you should carry a spare tire with you because that is an unusual size. Some tires are made that are folding and are easier to carry, I do not know if there are any 27 X 1 1/4 folding tires or if they are all non-folding wire bead.
I think you would be happier with a 24 tooth granny gear (smallest chainring on your triple crankset).
Have the headset, hubs and bottom bracket had their wheel bearings cleaned and re-greased? That is not part of a standard bike shop tune up. You should learn to do it yourself, the tools and a tube of Phil grease would cost less than having a shop do it. There might be you tube videos that can help learn how to do that.
I would be hesitant to invest much into the bike with more expensive parts unless you could use those parts on other bikes later. (I mention above that racks can be moved.) If you do your cross country trip and then want to upgrade, upgrading to a new bike would make more sense. But this bike could do a cross country trip, but a newer bike would offer better shifting.