how many miles are on your car and when did you do the swap? my main concern is how many miles you're getting with the raised compression on a stock block.
i had 55,000 miles on mine when i did the swap and now i have 61,000 miles. i still havent had it tuned yet either. im getting my dyno tune in the next 2 weeks though. your car should be fine with a good tune. on my last tank of gas i got 20 mpg. not bad.
I had about 58,000 on it when I did the swap. I now have about 78,000 and the car runs strong. A little difference from stock in terms of gas mileage. Maybe 2mpg better. (Exhaust mostly.)
I did the swap at 76,000 miles. The check engine light used to come on, but that went away after the tune. Not sure about gas mileage, I do all city driving, and have been having fun getting on it. I'm not really concerned though, it's worth it.
Everything else being equal (no further mods), I really doubt you'll see a change (except due to a lead foot), in fact, it may get a little better, since the higher compression engine will run more efficiently.