My Dad bought a 154 LoBoy about the same day I bought my 982 and 50C deck. I forget what mower deck Dad's 154 had, seems like might have been a 60 inch. Engine was getting a little tired, they run hot and overflow the coolant bypass, only cure is an engine rebuild, and that isn't cheap. The tractor mowed great, better cut quality than most old IH decks. It sold for $1300 in 2006 at Dad's last equipment auction, it looked pretty rough. I don't think the guy that bought it EVER ran a manual transmission, especially one without synchronizers. Last I heard the guy drove it into a clothes line pole, lots of grill, hood, & radiator damage. Last thing Dad did to it was spend over $400 at his local IH shop to rebuild the pto clutch, He did the removal & replacement. Common repair too.
10 acres is a LOT of ground to cover. Especially with an older machine. I used to mow 20 acres of alfalfa with our 6 ft rotary mower running 5 mph or Bush-Hog, and chop up to 30 acres of corn stalks a day with same tractor & mower. I still have that tractor, might get a little wider mower to cover that much ground now, run a little slower but do better job.
Six years ago I bought a Cub Cadet LZ54 TANK commercial zero turn mower I've mowed my 2.3 acres every week or ten days, roughly 15-16 times each year. Put right at 25 hours a year on it, never had a break-down, do one engine oil & filter change a year and grease it 2 maybe 3 times a year. If I had 10 acres to mow, I'd be real tempted to use the TANK. i have it, it could do the job, but it rides REALLY rough. A big rotary mower behind either of my two FARMALL tractors would be much less painful to mow 10 acres.
I see disappointment trying to keep 10 acres mowed with a 154. Something newer would be more reliable, I'd also consider how rough whatever you chose rides a consideration too. BIG tall tires tend to ride better.