steering problems

[Snowtractor]

ah peanuts, rods are dirt cheap , bearings are dirt cheap, mine was exactly as you describe and now a slight breeze will rotate the plate. So there are pits , big deal. As long as it is still solid then its just cosmetic in a place you will be hard pressed to see and only when the engine side covers are off and you stick your head inside the engine housing. If pits are such a concern use bondo on them.
My plate was so seized I had to cut the rods to get the plate down and out of the carrier . The clevis pins were siezed and I could not rotate or remove them to get the plate and mount out. But with some time and a torch and hammer everything came apart and its cleaned up and all together again, using the same hardware...and well greased. I also welded up the oringinal rods afer using heat and a vise grip to turn in and turn out the rods from the clevises ( clevi? )because they were so seized. Oh and I had to drill out the cotter pins as they had rust welded themselves to the pins. Clevis pins, clevises, rods ,cotter pins ,bearings are all common and reasonably inexpensive in most places ( not here though ) so you do not even have to clean that up , just replace it.
YOu could get a T16 manual and try to BS a tiller bar and brake system from that , but they use 4 tiller bars and you'll just be hacking up a MKII and you'll likely have a S*#TLOAD more work for a jury rigged job that might kill you at 30 mph.
Sean

ps I should add I removed the plate on my back in the snow at -25degrees and fried a grinder because it got too much frost in it during its heating and cooling cycles. So it takes a bit of work but the end result is worth it..along with the story. Somehow its less satisfying saying "yup I bought this wreck hired someone to restore it and now drive it..."