Can a Magus deliver touch spells via Spellstrike(Su) while using a melee reach weapon such as the whip?
At 2nd level, whenever a magus casts a spell with a range of “touch” from the magus spell list, he can deliver the spell through any weapon he is wielding as part of a melee attack.
The whip is treated as a melee weapon with 15-foot reach, though you don’t threaten the area into which you can make an attack.
The weapon is "melee" however the Spellstrike doesn't mention the weapon needing to be melee, but instead the attack. (In the same sense that this wouldn't work if a melee weapon was being thrown at an opponent).