GL 1000 question on exhaust?

[Tim's Wing]

Hello
recently I purchased a stock muffler set up..
Questions

The muffler is off a 1975 with 5 k miles will it fit my 78?
Pros and cons? I still have the 78 muffler its rusty though.

Question 2 should I blast it and paint it?
Any ideas on what brand paint I should use?

Thank you so much.

Love this bike