I rebuilding my 914 street only use 2.7 6 engine in my 914. I can rebuild to stock configuration or I can modify this engine with higher compression add PMO carbs and twin plug ignition and other goodies. The additional extra cost would be about $7000 over the stock rebuild. I have rebuilt several of these 2.7 and modified them on 911 cars. But, Is it worth spending the extra money doing this when it comes time to sell a 914 with a beefed up engine 4 of 5 years from now. Its plenty fast and fun with the stock 2.7 liter.

Twin plug might be overkill, but bigger valves, carbs and solex cams or similar is what I would do.

Will you get your money back out of it? Likely not.

Will it add value?
Bills for cams, pistons and a set of PMO's?
Hard not to see the PMO's.

A well sorted /6 will always add value, just not as much as you'd like.

I did:
J&E pistons. $1K provided you have Mahle Cyls.
Good used Webers/ intakes. $2.5K
DC30 cams. $600
Good used Electromotive HPV-1 ignition. $300
No need for twin plugging.

Adds about 25HP, sounds better, and looks more like a racing Porsche rather than the back of a washing machine under the lid.

Sounds like you have plenty of experience but my recommendation is that cars with uncertain engine histories are very tough sales. Well built motors with documented build histories do bring a premium. Not so sure you will get all of your money back, but it could make the difference between selling and sitting on it.

Secondly I personally do not care for CIS motors. This early injection rips the heart out of these engines and robs all of the "zing" that makes these such great motors.

I personally downgrade the value of CIS equipped cars. I Wanna hear and feel that flat six snap, not a sewing machine. Strictly my personal opinion.

Question: What's the reason for the rebuild?

Does it have bad leak-down numbers?

Like others are saying, rebuilding a 911 engine with plans on getting that money back when selling....doesn't happen.

Build how you like it and take the loss with smiles and fond memories of the fun.

Twin plug is not needed on an engine under 10.5:1 CR (from what I've been told)

If the leak-down are good and you just want a little more 'umph' you can put in SC grind cams and keep everything else, including the CIS. Let me know if that's of interest to you, as I was planning this route before finding more and more issues as the teardown proceeded. I have a set of 3 bearing SC grinds. Would be a CHEAP way to boost power on the top-end.

If you feel you will have more fun in a modified car, then spend the money on it. 4 to 5 years is a long time.

Cheap and east is how Nate was going, SC cams and leave the rest alone. I have this set up in my car and it is plenty peppy and responsive. Since you are 911 engine build experienced, the work is super easy and parts are cheap. Worst case, you decide you want more so you pull the cams, change the pistons, and add what other bits you want. My goal was a budget built /6 for a college kid. I graduated in 2005