I have them close but Buu still has the power advantage, on top of that, Buu has infinite stamina and broken regeneration, so I'd still say he wins.
<div class='spoiler_toggle'>Spoiler: click to toggle</div><div class="spoiler" style="display:none;">Base Goku: 1,500
General Rild: 1,350
-Hyper Mega Rild: 2,250
Gohan-Buu: 1,000
Super Mega Cannon Sigma: 750
-Neji: 300
-Rivet: 225
-Veise: 225
-Nutt: 150
Personally, I only have Rild marginally above Gohan Boo. With that, the way Goku and Trunks commented on Rild's power eclipsing any of the previous GT villains seems to show that bringing in this weakling will make no difference. Even outside of power, Boo has a far better moveset with regeneration, Chocolate Beam and absorption.
They shouldn't be very close to Base Rild at all, and he was the first guy to surpass Gohan Boo. Adding Nutt to the equation should not change a whole lot.