Don't be too bummed. I ran into the exact same thing with my L175. Bought the tractor because the seller said it needed a little work but would run fine. Had 300 hours on it. What he didn't tell me was that the air cleaner had come loose while it was running and it had sucked a bunch of dust into the engine. Also neglected to tell me that he had then used starting fluid on it trying to get it running after that... Sigh... Unfortunately, I've been down this road before....
How many hours are on the tractor?
Sounds like you got it at a decent price, so a bit of elbow grease and you'll be fine. It's a good little tractor.
If the unit doesn't have a zillion hours on it, you might get away with just honing the cylinders, new rings and gaskets if you want to go really cheap. Likely ~$350 or so.
If you want to do it right because you intend to hang onto it, then likely about $1000 for a full rebuild that includes pistons, rings, bearings, gaskets, head work, etc.
The last option is the obvious one which would be to just pull start it each time you want to use it. If it was running fine when you bought it, it would be a option for the time being.
Not trying to rain on your parade as it sounds like a nice little tractor. I think you likely did fine since it has the loader on it.
Please don't give up and keep us posted.
Kind regards,
Steve