Hi back to ya!

A 19 horse motor is fairly chunky for a lawn tractor.
If your machine does not have more than one PTO available and you don’t have an auxiliary shaft to feed accessories then your engine is really oversized for the frame or what it’s setup for.
I have a 14 hp John Deere 172 model with a Kawasaki engine. It has a 38“ deck and it has plenty of power.
I have no idea the size alternator and cannot look it up for you, as I’m not home.
It has taillights bulbs for head lights though.


I have seen some PTO clutches, on car air conditioning compressors, draw 4 amperes to as high as 10 amperes of magnetic clamping force.
How you use that through gear ratios of belts and pulleys is another set of calculations left to clutch people.
Most car A/C’s can need two or more tons of cooling.
They are not insulated and they are glass bubbles!

One ton of refrigeration is equal, in electric motor power, of 746 watts of work.

When converting to gasoline engine power to equal numbers things get distorted again!
Like, if you believe you can run a vacuum cleaner that peaks @4.5 hp on a 110v wall plug limited to 20 amperes is totally marketing bunk!
4.5 hp X 746 watts = 3,357 watts. Divide by applied voltage of 110v = 30.5 amperes.
Twisting around this stuff in relation to alternators with a 60 to 80% duty cycle can be a puzzle too!
So, I think that the engine you are replacing had a larger electrical capacity than you ever used.
It was designed to fit into many other applications.
So, it was produced to sell more of them for a lower or equal cost as a smaller unit.
Over kill to market is a safer method of customer happiness overall!
Nothing Runs Like a Deere!
I have had my JD/ Kawasaki for almost 30 years with the same spark plug let alone the engine but the seat has cracked vinyl!

The engine you are looking to get should be setup to do NEARLY equal work that your mower is doing now.
I assume you are staying with overhead valves and nearly the same horsepower?
Like I said and IMHO your electrical load is probably quite a bit smaller than the old engine was setup to do.

Just take what comes with the engine that fits your work load.

Phil