If you can get by with the smaller capacity and it looks to be in half way decent shape, I would say jump on it. Pick it up for cheap, upgrade the head and put new bearings and a belt on while you do it. Practically new and 1/3 to 1/2 the price for top of the line version of a small model. Just do a good look over to make sure if hasn't sat out in the rain and that the tables are straight.
The castings look to be the same as the other recent era craftsman/grizzly/etc. 6" jointers, so you can get this one which will fit for sure: https://shelixheads.com/SHELIX-heads...r_%2837-196%29
Or you can do some digging and more than likely this is the same shelix head but on sale:
I have some more info on the generic 6" jointer head somewhere, I'll PM you if I can find it.
Edit, found more info, but it is PDF version so not sure if I can attach that in private messages here. Apologies in advance for mixed units... If you can do some measurements before buying then see if it matches these:
*Overall length of generic 6" shelix head(sold as H7764 by grizzly) is ~9.4"
*outside/free end is 15mm i.d. for the bearing, ~.515" long to the shoulder. (may or may not be able to see this though end of bearing block)
*drive side end takes 17mm i.d. bearing, keyed drive shaft sticks out ~2.128" past the bearing and takes a .625" i.d. pully
*Most critical! Cutter diameter is 63mm -- if the knives are set correctly, wrap a strip of paper around the head touching the tips of the knives and forming as good a circle as you can make it hold. Mark where it overlaps and from pi you get that an unwrapped length of ~7 7/8" max is the same head size as the H7764. There is another generic 6" head that is exactly the same except for a slightly larger cutting diameter. If your circumference measurement is more like 8" to 8 1/4" then it is the larger size.