ANDREW COFFEY - no one answered Your gas tank question.... I had a 72 (same as Your 73) with a K241 Kohler, I modified My K161/181 gas tank mount and used the stock 5 quart gas tank for MANY years, but a 5 quart tank on a 10 HP engine means many gas stops while working. You should be able to fit the stock 8 quart gas tank from a K241 (10 hp) K301 (12 hp) or K321 (14 hp)engine onto Your K241 and still have the hood close properly.
I put a K321 (14 hp) engine in My 72 about 1-1/2 yrs ago and used the new replacement 8 quart plastic gas tank and IT WILL NOT FIT Without Modifications. A good clean used tank from a sponsor above is Your best bet. Son & I did make a "custom fuel cell" for the K321 & 72 tractor, held about 3 gallons of fuel, braided stainless steel fuel lines, tank was "sumped" so every drop of fuel drained but We suffered a fatigue crack & fracture on one of the mounts and We're going to start from scratch on a whole new tank this time. Same plan, same parts, same size, just a different fabrication method and design. I LOVE rebuilding things at least twice!