Not really. There are plenty of flat covers that originally came with gaskets.
The simple fact is gasket or not when it was new doesn't matter in the least. The only time I use gaskets is when the gasket is important for proper clearance or when the mating surface is completely above the fluid level and designed to be removed easily.
If I use a paper gasket I don't use silicone on it. This is pointless. Silicone just makes a mess out of it if you ever need to take it apart and makes it look like crap. I smear a thin coat of lubriplate over gaskets like this, torque whatever it is properly and it'll never leak. When you take it apart in 30 years the gasket will come right off in one piece too.
If you have to use a gasket below a fluid level gasgacinch works far, far better than silicone does. It's amazing stuff and that's what it's intended for.
If your PTO covers leak it's because you didn't clean it properly or apply silicone evenly. A 1/16" bead is all that's necessary and a tiny dap on each bolt thread if the bolt holes are through tapped like msot PTO ports are.