[AndrewMac]

If you do buy the early 78-9 SC you'd better be sure that the oil scavenging updates were done. If not the engine may have suffered from inadequate lubrication and cooling at high sustained speeds. Also the standard upgrades like oil fed tensioners, turbo valve covers should be in place by now. As I recall there may be an associaed chain ramp upgrade that accompanies the tensioner update. And by now the fan should have been updated to an 11 blade larger diameter fan.

Early CIS sytems used a plastic set of fuel lines which should be immediately changed to steel if not done already. (see thread on fire claims for 911s). If you're into creature comforts from I believe 80 on they came with cruise, power windows as pretty standard options. If you buy a targa the top mechanism is also revised to a roller style which is nicer if not 'better'. Maybe sway bars were also larger by a fraction from 80, but not positive.

I own a 78 and a late 81. I think for daily driving the 81 is a bit nicer for the cruise control on longer trips. I also think the targa top mechanism is a worthwhile consideration.

I say if you want a daily driver go newer SC. If you want to build a track rat go pre-80. Bruce Andeson's advice holds true here. Buy the newest 911 you can afford, all things being equal.