Painting Intake Manifold And Valve Covers?

oklahoma is red dirt country for sure, lol. i'm glad i don't ever have to drive on a dirt road here though. at least not in my stang. as far as your master cylinder being different, do you have 4 wheel disc brakes by chance? looks like it may be an svo master cylinder. if not, then someone may have just put an earlier model master cylinder on there, pre 87 or so. not sure why someone would have done that though

The master cylinder is likely matched up with your brake system and unless you want to change the pedal feel (harder or softer) or if it's leaking or not working, you should leave it as is. The technology hasn't really changed much on them, just the looks.

As for cleaning the engine, I just saw this the other day and this looks like the best way to do it.
http://www.jaylenosgarage.com/extras/car-care/detail-your-car---with-steam/index.shtml

So you'd need to know some more info before you know if you have the correct master cylinder. First off, you need to know the bore size of the master cylinder as well as the piston size of all 4 of your calipers in order to do the math and see if it is correct. If your pedal is soft, and you have the correct master cylinder for your calipers, then you likely just need to bleed the brakes. If the bore size is too small in your master cylinder for the size of the pistons in your calipers, you will have mushy (soft) brakes. If the bore size is too big, your brakes will be hard. In my car, I have cobra 13 in. fronts and SN95 regular disks in the rear and a 94/95 GT master cylinder (1.0 bore size) and my brakes are a little too hard so I want to put on the cobra master cylinder which has a 15/16 bore size and will give me the correct factory pedal feel.

No idea on the cost for cleaning that engine bay, I'd guess $150 but totally depends on local rates for ya.