[T3] Engine Tin and Such

[Know One]

Finally getting around to re-assembling my engine outerwear after a year of occasionally sandblasting the tin. 

I know I will have to alter the tin to get my early tin to fit an engine with newer tin.

Should the cast aluminum fan housing be painted?
I know that the steel tin should be painted black for heat dissipation, but should the fan housing?

Reading one of the manuals, it notes that the bolts holding the fan housing are different lengths.
Which is which and how long are they?

The bolts I took out have serrations in the threads, and I suspect that they should not be re-used as they could cut into the threaded holes in the engine case. Am I correct?

Jeff '67 Sqbk