Re: what kind of paint to use?

I totally agree with that preparation is the key to a successful paint job. I had my metal pieces sandblasted while I had it apart and it had that matte looking finish as previously mentioned. They were painted as pieces.
Duplicolor seft etching primer, then the two part auto primer, then the Rustoleum with automotive enamel hardener. Wet sanding between applications with 600 wet or dry paper made the surface smooth as a baby's behind.
Most dry spray is obviously prevented with a good "wet coat" which is almost impossible when spaying any large size with a rattle can.
I am not trying to convince you to use the Rustoleum but cost wise I believe it to be a good choice. I have never used the Mercury phantom paint so I don't know how thick it is out of the can. The Rustoleum is thick enough out of the can that one quart will more than suffice for painting one motor.
The photos aren't real good since these parts have been in my basement "curing" for a couple of weeks and have collected a little dust and the spots on the mounting bracket are water droplets from the rain we got last night.
Anyway, good look with your project and remember to not get in a hurry!!! Slow and time consuming will get a little frustrating but the end result will be worth it.