Is this a single valve cover gasket leak?

fix it yourself, do both as they are both leaking. Rent all the tools AutoZone will allow you to take, harbor freight everything else except the jack stands. I did my 1994 Q45 infinity in the dead of winter, and that vehicle was a rust bucket from Michigan, had no parts available, 20 year old seized joints, and was designed by a masochistic Satan worshiper that did not want it EVER taken apart.
You can do this! Just take your time.

 

Interesting review, Snap-On seems to have gone down a bit. I have some Snap-On tools, but the majority are Craftsman. I have never had a problem with them. Snap-On are good, but not really worth the money, IMHO. I have one Snap-On ratcheting Screwdriver that is slipping and I need to get it replaced. Back in the day, they used to have a store in St. Louis. I guess I should contact them for a replacement.

 

I see they use a Proto calibration block.

Proto makes good handyman tools and gets forgotten.

In refinery settings where tools get bought by the Millions of dollars each year, Proto is a common brand and I can't say I've ever had a complaint with breaking them, even abused. (hammers to ratchets, etc.)