Building a fixie with an old Norco frame with Tange 900 double-butted tubing.

The bike was made for 27 inch wheels, but I was planning on spreading the mounts to fit 700C's.

The fork weighs a damn ton and am hoping to replace it, but two things concern me:

1. It is one of the curved style forks common on old road bikes, in considering a new fork should I look for one that is the same style, or does that affect the bike?
2. Can I make use of a 700C fork without real detriment to the ride-ability of the bike? I'm worried that an alteration in the size of the fork will offset angle with the rear wheel.

If I'm going with a new fork, I may or may not switch the headset to threadless. It is a 1 inch steer tube... so given that... should I switchover to threadless... or just get a lighter quill stem and threaded fork?

Thanks for any help/advice you can give!

-LC