hey guys, I have a 78 911sc that needs an engine rebuild. The engine has about 160K on it, it has had the top end done once but the valve guides are leaking again so I figured since I will be tearing into it anyway, I can get some more power out of it.

I have been reading in different places that a swap is a better and often cheaper way to go than rebuiding my current engine. Most people seem to say I can swap in a 3.6 for around 12k. A pretty thorough rebuild on my 3.0 will cost anywhere from 7 to 10 depending on what I find when it is opened up, and how much power I try to get out of it. I understand that the Jetronic is the limiting factor on 3.0 but I HAVE TO stay emissions legal, so carbs are out.

I would love to hear other peoples opinions and experience on this. Right now I am leaning towards the swap.  

I have an 81 SC and a few years ago I rebuilt the engine on it, and I am now also considering a swap. It sounds like you are at least realistic about the price of the rebuild, when I did mine I thought I could get away with a rebuild for about 5 grand. It won't happen, plan on ten grand.
I did my motor about 175K. The costs just kept snowballing. You figure that you already have the motor apart, so why not upgrade here and upgrade there, it is really hard to stop. Plus you have to replace the worn parts. I did all new ss valves/springs/retainers, new higher comp pistons, cams, some head work, head studs etc......
Unfortunately my car won't pass emissions now, probably a valve guide(and no cat) so I am looking at tearing into the motor again(and a new exhaust).
For around 12-16 I can swap in a 3.6 with a better power band and it will pass emissions. I have been researching it for a while and it seems like the easier way to go. Several companies make kits out so all you have to do is find an engine. There are even several shops that get you the engine, so they will send you everything you need.