Goku absorbed the remaining energies of Vegeta+Trunks+Gohan+Piccolo AFTER they had been beaten to shit by Broly and were almost entirely powerless(the Saiyans, for example, were so weak that they had reverted back to their base levels.)
Round 1: Assuming Perfect Cell starts at FULL power, I just don't think this Goku could incapacitate/kill him before the amp wore off. Keep in mind, the single punch he used to beat/kill Broly in Movie 8 seemed to have tapped ALL of Goku's remaining energy -- the amp notwithstanding. Obviously that same punch wouldn't be enough to cause any lasting damage to Cell at all(*thx regen*), so Goku's best bet here would be to try and pack all of that energy into a single blast before it was expended, imo... But even in that scenario, his blast would have to be vastly more powerful than the first Kamehameha SSJ2 Gohan used against Perfect Cell, because even THAT wasn't sufficient to incapacitate him for *any* length of time...Let alone kill him: https://i.imgur.com/yS5pP5x.jpg https://i.imgur.com/JgUchJP.jpg https://i.imgur.com/UyxgI3g.jpg https://i.imgur.com/Po2Hob9.jpg
...And that blast was already FAR more powerful than what anyone else on the field could generate(the Z Fighters were awestruck by it.)
tl;dr
Do I think Movie 8/amped Goku can generate an attack powerful enough to incapacitate and/or kill a full power Perfect Cell? No, I really do not. So even IF Goku initially went into this battle stronger than Cell, ONE attack would burn-off the amp entirely... Then it'd be easy pickings for Cell regardless. /shrug
Round 2 is a no-brainer: SPC stomps.
__________________
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."
...So like I mentioned above: if Cell goes into this battle at FULL power, then it will take a blast FAR more powerful than the first Kamehameha SSJ2 Gohan struck him with, to have even the slightest chance of putting Cell down.
__________________
"I am tired of Earth. These people.
I am tired of being caught in the tangle of their lives."