In order to know your voltage drop you have to know what is coming out of hte alternator.

10V at idle with 12V revved up is BAD.

11.5v at idle with 14 revved is also bad.

Since we have no idea where you voltmeter is actually tied into the system it's hard to say what it's reading. If you simply bolted the two ammeter connections together and used that point as the freed for the voltmeter then you should be reading alternator out put and if it's that low you have serious issues.

We may as well start at the beginning ...

What is the reading at the battery positive - (use engine block for ground)

engine off -
engine at idle -
engine at 2500 rpm -

What is the reading at the alternator stud - (use engine block for ground)

engine off -
engine at idle -
engine at 2500 rpm -

What is the reading at the coil positive - (use engine block for ground)

engine off -
engine at idle -
engine at 2500 rpm -

Once we have these we can go from there

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.