Tell tales are for " dummies "------Install a new impeller every 5 years !!-----Test your overheat light.----Better yet install an overheat warning horn and test it every year..
Agreed.-----At one time I corrected some sellers with motors listed as 10 or more years newer then they were.-------Amazing replies and I do not do it anymore.
That wire goes from carburetor area to under the flywheel.-----Part of timing advance for starting and warmup.----Check oil in lower unit.---Check shift adjustment.
I would say that 20" is LONGSHAFT.--------25" is an EXTRA LONGSHAFT.-----The boat shown will likely work with a 20" motor.-------But it looks like there is some work to be done before you can hang a motor on that transom.
I think you need to do a complete , very complete evaluation of this motor BEFORE spending any money for parts.----Where is it ( location ) that this is the best deal you can find ?