95 Compression

I've been fixing up a trashed 95 2 door Yukon little by little, but to get straight to the point, my Yukon has a 200 horse 350 on TBI. That's fine, its setup for fuel economy, but since mine is lifted 4 inches with mudgrips, it feels weak to me. Now, I've dealt with a good number of smallblocks in various cars, and while 200hp is a fairly well-rounded number for a 4 wheel drive that's also geared high for highway use, in the back of my mind I think this: generally, 200 horsepower is pathetic for a 350, I've seen old L69 305 HO's put out more with little modification. On the other hand, its turning out to be a good workhorse and gets ~14MPG even with the heavy mag wheels & tires it has to lug around. My question is this: If it comes to a need to refresh this 350, and assuming I leave everything else completely stock, and I don't mod my TBI or ECM in any way, what would it do to my highway fuel economy if I replace the lower compression pistons with flat tops? In my mind, fuel economy wouldn't really change and if it did, a miniscule amount, but since I don't usually suffer from LFS (Lead Foot Syndrome) I'd think I could keep a lower RPM going 55-60 down the highway (currently 1500RPM with 4L60E tranny), be able to pull better, etc w/o sacrificing my fuel economy. Basically all I plan on using it for anyway is to haul my big butt around here & there, maybe carry tools, and I'll need it for towing my Camaro to and from body & exhaust shops, but an extra 50-70 horsepower would be very useful, while not over the top.

Any increase in compression within reason will provide better power and mileage, just can't go over about 9-9.5:1 without requiring high test.

That's along the lines of what I was thinking. I know I'd need 93 octane gas for the flat tops, and if I can find that octane booster I used to get so cheap (10pts for 27 gal) it won't be that much of a problem. My other car has to have premium anyway, because it reacts to ethanol content so it's not a real big change to me.