By the looks of things that kind of bike is fine for a fixie conversion. Make sure it fits you first.
Things to be wary of:
The frame will probably take 27" wheels. Modern wheels are 700c (8 mm smaller in diameter), with a few fairly cost prohibitive exceptions. Result = if you put modern wheels on the frame then modern brake calipers are unlikely to reach the rim. This can be got around if you don't mid using the brake calipers that are already on the bike, they'll usually reach - you just wont stop terribly well. Or you can get long reach brake (not all of them will reach). Or you can make a drop bolt >
http://www.bikesmoveus.com.au/showthread.php?t=4557, then you can mount whatever brake you want.
It's likely to have a older / cheaper style crankset. The largest chainring will be permanently attached to the drive-side crank. This isn't a terribly bad thing just means you may have to buy a huge rear sprocket to lower the gear. Or buy a new / different crankset.