In the Buu saga Goku was able to lift 40 tons in base, using the ssj multipliers, ssj3 would be able to list 16,000 tons. To calculate the power increase of ssjgssj we must first find out at minimum how powerful is Beerus? Goku at the end of the namek arc had a power level of 3,000,000, this power level we will use to determine the power of Beerus. Using the multipliers ssj3 Goku whould be 1,200,000,000 and then Beerus using a major battle difference would be 1,320,000,000 with a flick. Since a flick is 1/3,000 of your power this means Beerus supressed is 3,960,000,000,000. Assuming this is 1% of his power his max power would be 396,000,000,000,000. Using Akira Toriyama's comparison of Beerus and ssjg Goku would put ssjg Goku at 237,600,000,000,000. Using a major power difference to calculate the power of ssjgssj would be 261,360,000,000,000. Making his lifting strenght 3,484,800,000 tons. Since ssj2 Goku was capable of solar system busting his ki output in ssj 3 was 4 solar system busting which is also his endurance. This would put ssjgssj Goku's ki output/endurance at 871,200 solar systems. Lastly speed would be at instant because of the instant transmission.