So many questions...
 

I'll try and be brief.

The bike: Old Simoncini. Columbus tubing, rusting in spots. Campy hubs (Record) and rims. Campy (Breve??) cranks and rings. Modolo bars. Miche post. All in all a pretty nice bike.

I plan on a single speed, not fixed (yet).

The questions: What do I do first? I have taken almost everything off and started cleaning. Do I worry about painting yet or take it to the LBS and have them check it out? Do I keep the 40 ring and match it to a 16? Is that good for a first timer who is fairly fit and planning to ride mostly flat? I don't have the knowledge or tools to build the rear gear so what should I expect to pay to have them space the 16, shorten the chain and align the chain? I like the look of bullhorns so I plan on flipping the bars and cutting them down and using some cheap levers.

Any answers or suggestions would be much appreciated. Thanks for the time.

What kind of dropouts does the frame have? If not horizontal, you might need a Surly Singulator for chain tension. The rear casette hub is the 1st point of attention, you need to acquire some spacers or a good SS conversion kit (a new SS hub would be nice) Apart from that, 40-16 sounds fine, if little on the low side for flat. I'd recommend 42-16 or similar.

Questions
 

The most important thing is chain line. That is the first thing to address. Get the spacers and make sure it is correct before you ride it. Like the last post said. If you don't have sloping drop outs then you will need a chain tensioner of some sort to keep the chain in tension. You can use the Deraileur that is on the bike by locking it with the limiting screws so that it can't move in or out. That would be the cheapest but least pleasing looking option. If the drop outs are mostly horizontal then just adjust the chain tension by moving the wheel back in the drop out to adjust chain tension. Remember not to tight, should have about 1/2 inch or less of vertical play at the middle of the span between front and back ring. Fixed gear is another matter and has it's own set of requirements as to hubs. Don't worry about painting until you find out if you like it. That should be the last thing you do. Good luck.

fixedgearhead