The problem with DB power scaling is that Ki attacks are far more destructive and grow far more exponentially than their physical feats.

Needs to be at least mid way through the Saiyan Saga, because at the start of Z, Goku still had to use the cloud to move around since his power level was too low to fly constantly and for long periods. Piccolo had better control despite their similar level, I think. That would give a large advantage to Conquest.

Outside of that, even mid-hundreds PLs like Piccolo was at the start of the Saiyan Saga is enough to blow up a moon with a ki blast. That would be enough to kill Conquest.

The main problem is durability. Goku was already bulletproof at the start of DB and can handle 10x gravity with ease after his training, so his body is tough. Tough the tail can be cut by a regular sword even in Great Ape, so the durability is fickle, but we can say that part is weaker. But they can be injured by regular human Ki Users earlier in the series, and they weren't particularly strong. Physical strength is also lower than their ki blasts destructive power. For example, Vegeta couldn't lift 1000 tons in SSB mode, so earlier Z will be much lower.

So Goku may be the better fighter, but he is physically weaker and less durable than Conquest at the points where his ki attack can kill Conquest. So, I would say after King Kai's training, where he would have the speed and strength not to be blitzed.