I confess that I've yet to play as Pericles, let alone Pericles with Space in mind, so commentary below is 'theoretical'.
I think that he's well placed to set Greece up for a solid position by the mid-game and then use that to head towards a Space win, but he doesn't really strike me as a real stand-out for a Space-oriented leader as little is especially late-game oriented.
I would suggest that two of the traits that tend to diminish over the course of the game are indeed Creative and Philosophical - neither are useless towards the end, but unassisted border pops and cheaper early-mid game cultural buildings I believe are of more benefit up to the mid-game, while popping Great People becomes increasingly harder and typically their value becomes less as the game progresses. I am mindful that these are general points, and you can certainly leverage late-game Great People effectively with some thought, while cheap Universities and therefore prospectively a fast-build Oxford University too can be a vital difference - especially if a good chunk of your science haul was derived from Monasteries and you need to terminate their bonus to press on to Physics et al.
Greece's unique unit (Ancient Era) and unique building (Classical Era albeit 'Hit Singles' bonus) again make the run up to or into the mid-game quite OK, but the leap from here to a Space win is pretty big.
With all that said, a 'transitional' approach does have some merit, and as futurehermit suggests, you can keep the war effort up with technological superiority and fairly fast-fixed happiness and culture - especially in the mid-game. Should you wish to 'turtle' from this point, then Space would seem to be as an appropriate target as any - although as you noted at the outset, Cultural presents itself as a good alternative.
