I don't load for 5.45x39 but I do for 5.56x45 (223rem). The bullet diameter of 5.56x45 is .224" and I THINK that the bullet diameter for the 5.45x39 is .215". You definitely cannot use 5.56x45 bullets for 5.45x39.
The Russians are known for not using the same diameter bullets as we do. Their 9x18 Makarov bullet is a slightly different diameter from our (and Europe's) 9mm. Their 7.62x39, 7.62x54r, 7.62x25 bullets are not our .308 diameter "7.62" bullets either.
I have loaded SPs for game in 7.62x39 but the cost of handloading from new brass is steep for plinking ammo.
I would expect the same situation for 5.45x39 if someone did offer brass & bullets.
The AK usually destroys the cases anyways, so you would probably only get a load or two out of 'em before having to discard them.
I don't know of any load data for 5.45x39.
A quick search of www.midwayusa.com turned up nothing for brass or bullets in 5.45x39.
I hope the 5.45 comes back in plentiful and cheap fashion myself.
If not I expect to see a bunch of cheap AK74s on the market.