/6 or v8 swap?

Lol, I'm not sure going for worse milage would be ideal for this situation. 10 years ago I wanted to big block swap my tired small block manual suburban. It obviously got poor milage with the small block, I told her that the big block would be better cause it would have less effort to get the truck motivated with the bigger motor.......well I installed a big block, dual 40 series flowmaster, 2.5 pipe, aluminium intake and edelbrock carb. It definitely motivated the rig far more, sounded mean, 36" tires, 4" lift, big winch bumper, etc. But when she realized it didn't better the fuel economy she was not happy. Now, it could be driving habits that killed that possibility. And while she was not happy with milage, she grinned ear to ear everytime she drove it, which was often. Wouldn't even turn the radio on, said she liked the sound of the cam rumbling through the 40 series. That said, she still has not forgotten about it, and throws it out there every time I start talking about engine swaps and upgrades......dang. Haha.