I would do the jointer and save for a replacement planner. In fact I did exactly that. Not worth a Byrd head on that machine. Had one for a few years, cut quality was excellent with sharp knives, but the noise is ferocious, and the depth of cut is is a real limitation. Spiral heads take more power and that machine barely has enough as delivered. Its great being able to joint and flatten boards irrespective of grain direction. You can get better steel than the stock knives for better edge retention, hard knots are a potential problem for any planer knife so proceed with caution. I use my jointer for tapers on table legs where I cant easily drum sand or plane out damage, so the spiral head is a real plus there.
"A good miter set up is like yoga pants: it makes everyone's butts look good." Prashun Patel