Look at my Garage. I covered off the 2.7 build I did for my track car there.
http://forums.pelicanparts.com/dto_garage.php?do=viewvehicle&vehicle_id=8702
I have a 2.7 with 9.5 JEs. I shimmed the cylinders / heads to get 9.8:1 compression.
I ported my heads to 36mm like a 2.7 RS.
At 9.8:1, you can run single plug. I ran 91 mixed with race gas at the track and straight 91 on the street.
I am running MSD, early HEs, and 34mm chokes in Webers with the PMO manifolds.
I have DC40 cams, you will want something like this as opposed to the E cams which are too peaky.
On the Dyno, this was within 5 HP of the engine in Magnus Walker's 277 car (2.6 short stroke with 10.5 and twin plug built by Andrew15). My torque curve was also a lot flatter.
If it you do go twin plug, do yourself a favour and use 2 EDIS distributorless ignition systems. You can do this all in for around $500. Either way, you will want to run an RS ignition curve.
Your trombone cooler will no longer provide enough cooling so you will need to add additional cooling.