If your going to be into it anyways I would do the orange instead of stock matte black. Might as well make it yours while you're at it.
I had a guy airbrush a tank for me years ago for an old bike. Tank was originally black but I as well had a small mishap that resulted in a large dent. I popped out the dent best I could and he finished it up with some bondo. When it was time for paint I was going to do stock black again but he said to trust him.
He sprayed the tank a bright silver, and then when that dried he mixed the clear coat with some black paint. He sprayed that on and with expert execution covered the silver with this black tinted clear coat. When it was dried the tank was black but with the deepest almost carbon fiber type effect as some of the silver base barely showed through. Super depth, looked an inch deep. Very cool.
How does that long winded story relate to your situation?. If you end up with a new tank I would urge you to try mixing some of that orange paint you were talking about and mix it with some clear and try a section on your old scrap tank and see if the results are interesting. I don't know if it would work as well with a dark base coat and lighter clear but what's to lose? Would be neat effect on new tank and fenders.