Higher compression will give you more power and MPG's per unit of gasoline. On a new build with ign. timing set you can run it on regular. As long as you don't get any build up of deposits on the pistons, etc. you should have no issues long term.
I just took apart a 2.8L engine that had some work done to the heads. The builder, an old friend, used 2.6L heads and matching intake. The intake side of these heads look like the 2.9L heads but the order of the intakes & exhaust are the same as the 2.8L. And you get only two exhaust ports per head! That's a throw back to the German origin of this engine design. It started out as a V4.
This engine is getting totally rebuilt with a Comp Cam (.424" lift), the head has bigger valves installed already but it needs new guides and a simple valve job to make it right. I might clean up the port while I'm at it too.
The carb will be a Weber 38 DGAS, sort of like the Holley 2 bbl as both throttles open at the same time where the Weber carb that came stock was the 32/36 DGV.
With a .020 over bore and some slightly high com. pistons I would bet this engine will make around 140+ HP. Maybe more but I'm being conservative.
The engine came out of and will return to a 1974 Capri that's been sitting in a garage for over 25 years. The current owner bought it in California back in the late 80's and drove it back to the Chicago area. He parked it in the winter and one spring in the early 90's he decided to redo the interior and that kept the car off the road that year and every year since.