Thanks for the recommendations and advice from everyone.
I am familiar with back bevels, use them on my hand planes for figured stock when necessary. I tried putting a back bevel on planer knives many years ago, worked with curly maple, but i didn't like the surface quality it left, scraping is a relatively harsh cut. It was much more difficult to hone the knives really sharp, that micro bevel is hard to ride on with a stone. And the knives got dull much faster. Granted this was long ago before I knew much, could no doubt get them sharper now.
I'm not ruling back bevels out, might as well try it if I get the planer running, but I am really impressed with the cut I get with shelix heads. They are not scraping, there is definitely positive rake. Hard to tell how much, I'll try to compare it to a straight knife head. But the carbide inserts are really sharp, stay that way for a LONG time, and it's easy to just replace or rotate one for a nick. But most of all the cut is clean and very smooth.
Tannewitz - thanks for the Boice Crane recommendation. Seems I've heard this before (from you?). I'm very open to alternatives, i will keep my eyes peeled for one. I bought the Delta because it showed up locally on Craigslist for peanuts, couldn't resist, but I could just repair the feed mechanism and sell it.
Right now the project is on a far back burner, no orders for rims at the moment, but lots of banjos to finish, wood and tools to sell. Maybe this winter.