hmm, well one piece would be easier to work with, you have cottered. they work, but overhauling is a pain. I had the chainline off on mine and the chain a bit too tight... so i taco'd the chainring and bent the spider arms to hell lol. running two brakes might not be the worst idea.

see if you can borrow somebody else's 700c's with tires to see if it clears. cheapest track wheelset i've seen after shipping is at bikeisland.com, dunno what availability is like.

i personally wouldn't dump all 300 in on this bike, those cottered cranks really are a pain to work with (though i like to do all repairs myself. keeps cost down and it's meditative)

edit: just saw the dropouts, they'll work but they're not much quality at all, this reassures me on my don't dump 300 on this bike stance