Aging Imperial Stout

I will be aging an imperial stout for 8 months. Question is, can I keg it for that long, or should I bottle it?

I'd put it in the keg. Once I started kegging the bottles job is to take up room on shelf.

So you can keg it for that long under forced carbonation no problem?

If I'm going to keg it for awhile as it ages then I hook it up with the other kegs that are in the kezzer. There is no reason you can't keg it and then treat it just as you would if you had bottled it, except I do hook it up to CO2 and vent the keg a couple of times to get the air off the top of the keg.