Unfortunately, I know more about copyright law than I care to.
Technically, it is NEVER right to put someone else's legal, registered, trademark on your personal creation. Sadly, this would include Partsrites and restoration projects unless used with the express permission of the current trademark owner. Sometimes it's okay to use a text-only trademark so long as it is in an unassociated region of industry, or a geographical region of business that won't threaten the trademark owner's primary customer base. For manufacturers and retailers who engage in commerce nationally or internationally this creates a whole other set of issues - US Copyright Law is not necessarily recognized or enforced in foreign countries. Therefore, a US-based entity will have to register their patent, trademark, or other intellectual property in any or every other sovereign nation in which they intend to engage in commerce. (This is why there are so many Mosrite "fakes" coming out of Japan and Asia.)
Any time and under any circumstances (and I cannot stress this enough), if you knowingly OR unknowingly infringe on another copyright holder, trademark owner, or any other intellectual property, you can be liable for charges from civil law clear up to federal law (and then some) - resulting in anything from having the infringing material (this could include an entire guitar) confiscated to facing fines, penalties, and even imprisonment.
Anyone who manufactures, replicates, duplicates, purchases or resells a "Mosrite of California" waterslide decal is liable for facing criminal charges. Anyone who manufactures or purchases "reproduction" pickups with the "Mosrite of California" logo impressed on the top is likewise liable for facing criminal charges.
However, since Uncle Sam has better things to do (like fine a fisherman $50,000 for catching a big fish in the ocean, or raiding Gibson USA's lumber yard), so they're not usually too quick to snoop folks out and go after them. Especially when, in the words of an FBI agent I spoke with in Sacramento over going after someone who had illegally signed and cashed some checks in our company's name, 'it really hinges on the dollar amount lost.' So when you have big-time crooks like the big-wigs who used to run Enron easily within the Feds' grasp, they're not likely to come after a retired grandpa who bought a decal for $5 and put it on his home-made guitar. So this usually leaves it in the hands of the trademark owner to go after these folks and press civil charges. If they plead loud enough, they may be able to get criminal charges filed against the offender. But usually the trademark owner will have to retain an attorney (it's best if it's one who specializes in copyright law) and have them send a 'Cease and Desist' letter. If the offender keeps up the illegal activity then they'll probably face a lawsuit. Most of these cases don't incur a loss large enough to justify the trademark owner investing the time or money to pursue the case.
The real question then is - how willing are you to risk it? I would hate to be
that one guy who get's caught and they make an example out of.
Because of all of these things - M-3 California feels it's best not to get involved in anything that could result in copyright infringements. You will never be able to order a "Mosrite" or "Gospel" branded guitar from us. We've had many people purchase supposedly-NOS "Mosrite of California" pickup covers and request that we use them in fulfilling their pickup order. Sorry, no can do. The only time we will wind pickups for a "Mosrite" branded pickup cover if it is a truly original part, a restoration or rewind job. We usually require the customer to send the entire pickup - not just the covers, when restoring it.
In the case of the Gospel trademark, Bob Shade is the legal trademark owner. Even if Bob were to be a sport and allow you to do it yourself, it would most certainly be best to contact him directly and obtain his okey-dokey first. If nothing else, at least as a humble show of respect for his fine product and for his wishes. Bob, maybe you can help out folks who want to restore their Gospel models by providing waterslide decals?
In light of this info, it would probably likewise be best to contact Fillmore or Dana Moseley before purchasing Mosrite decals and using them on your restorations. And especially The Ventures. They are sick and tired of people making "The Ventures Model" decals and putting them on their guitars. There are way too many Ventures model Mosrites running around out there that were never sanctioned by The Ventures after the endorsement ended around 1968.
, and can cost us big $$$ if we decide to fight it 
. Honest people like Bob produce a quality product, of which they are justly proud, and that pride carries over to people who own, and want to own a "Hallmark." 