Smoke on cold start is bad. A >little< blue smoke probably okay, white smoke not happy (unless it's chilly out, then it'll do it anyway). Make sure you do a compression test, make sure it idles smoothly. If the transmission seems a little loud it's probably okay yet, but disturbingly loud means a rebuild is due. Check for rust under the rear seats and around the hatch opening.
More than that . . . ask on www.nopistons.com or www.rx7club.com
J