I built an 8' mower many years ago, using blades from a Gravely that I bought surplus. They were about 1/2" thick, and 29.5" long. I built some spindles to fit a boat axle hub, and mounted the hub on the deck I built. Bolted the blades to the spindle, added a pulley to run from the mower engine, but later just added a right angle gearbox (1:1 ratio).
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When I saw your post looking for a 35" mower, it made me think about those blades, and how I built that mower. Seems you could do the same thing, only on a smaller scale. (One blade instead of three)It really wasn't that hard to do, and would make a good long term mower if you built it right. The hardest part would be getting the spindles made, but if you have a machine shop locally, they can do it in less than an hour with CNC. Add a little longer for manual lathes.
The blades I used were shorter than your requesting, but I considered bolting a sickle bar mower blade to the end of each blade, theoretically extending it about two inches in each direction, if you need that distance. Another way would be to just pick a mower (36" snapper?) with the right distance blade and buy a couple to use. Make the spindles to match the blade and your in business.
Good luck with it, and hollar if I can help.
Might also help if you add your location to your profile so people know what part of the country you are in.
David from jax