RE: Finishing for a TF GS P-51D
Assuming your going with a pretty scale rendition Id say yes use semi flat all over once your done. Take a look back on the thread I started of only Mustang specific photos and you will see that Uppupa Epops is not glossy except where they elected to leave the sheet metal natural like on the flaps where its very mirror like. This is not polished its just the finish the sheet metal has when its produced.
Yes at a glance your graphics look to be larger than needed for the TF Mustang. I have a shot of those same call outs on the real plane, should be posted in my thread. They could be 1/4.5 or something and thats why they are bigger or they made a mistake shipping them to you. They offer 1/4 and 1/5 according to the site right? Or maybe they are just the wrong scale and they dont know it.