WYATT - I think we're ALL really interested ( know I am!) in seeing your Wheatland 141 when it's done. You've really put a LOT of great work into it. Glad you're getting back working on it!
BILL J. - The white smoke is probably vapors from the breather cover. It's engine blow-by, little oil vapor, little water vapor. All engines do it. If the engine isn't using a lot of oil I wouldn't worry too much about it.
I mowed with a pretty stock 12 HP 129 & 44" deck for many years. I could occasionally slip the mule drive belt, but I suspect you'll bog the engine down on a K241 long before you slip a belt. If you slip a belt you better check your belt tensioners. You should be able to mow grass at a reasonable speed as long as the grass isn't real long, say 4-5 inches. Resonable pace is 3 MPH, more or less.
The 44" deck should throw clippings about 3 feet. I'd remove the deflector, I think they lead to windrowing, I've never used one. The speed-up pulley will make the deck pull harder, so I don't think it would be wise on a 10 HP tractor. If you had a smaller deck, then maybe.
I would leave the belt cover on the deck, think there's only 8-9 nuts, holding it on. They do help keep clippings from getting around the spindle pulleys, plus they keep fingers & toes from getting in the spindle drive belt. To be honest, I only remove(d) the cover on my 50C & 44A maybe once every year or two. I'd blow out the clippings, wipe the grease off the tops of the deck, make sure the idler pulley moved well, check belt condition and put the cover back on. If you don't get your tractor/mower WET, it won't rust. There's only been a couple times in my 49 yrs of mowing with CC's that I've "WASHED" a deck after mowing, and that was when I ended up mowing in the rain. The water soaked clippings were packed in so tight the mower would barely run. I do blow the tractor & mower off with compressed air after mowing every time. Compressed air doesn't promote rust.
You'll have to look closer at the steering wheel. There's normally a plastic bushing inside the top of the steering tube the steering shaft runs in. Sounds like the bushing has slid up allowing the shaft to wobble around. Several ways to fix that. Line the bushing OD up with the tube and press it down. I've used stainless steel worm gear hose clamps to clamp them to the steering tube before, or you could drill a small hole thru the tube into the bushing and insert a small short sheet metal screw. Dad removed the steering wheel and put a stack of 3/4" flat washers on the 70 years ago to cure it. These all work.
Ground speed fluctuations on a hydro is common. If it's excessive then you need to check for wear on the trunnion spring slot. Directions & repair procedure is in the FAQ's. I noramlly mow around 3 MPH, which is faster than 1st gear on my GD's, but slower than 2nd gear on my #72, about the same as 2nd gear on the #70. When the grass gets taller I'll mow slower, when it's sparce or shorter I'll mow faster. It all depends on what it looks like behind the tractor where I've mowed. I keep grass accumulation cleared from under the deck, keep the blades sharp, and keep the RPMs up so the mower runs fast enough to throw the clippings out of the deck and disburse them.
My K321 in my #72 is kinda a "fair weather tractor", it's a small flywheel K321, it's somewhat cooling limited. I normally try to mow with it when it's cooler, in the mid to low 70's, but have mowed light grass when it was mid to upper 80's. With the 982 it seems to have much more cooling capacity, but I still try to only mow when it's less than 90. That's more for ME than the tractor. The K241's should be O-K to run & mow in any temps as long as the grass screen is clear and the cooling fins are clean. When it's really hot I let the engines cool a lot longer before I shut them off. I may idle them with no load for 10-15 minutes.
