Is it possible to grind a pad using the original pad as the template without having the stock ? Need one fitted and trying to avoid shipping costs and trouble if possible.Any recomendations are appreciated.

If everything is 100% symmetrical about the center line of the mounting holes, it would work ok. I have never seen thing that are 100% so you might grind it close and do the finial fit later.

It is rare to find a pad with the same hole spacing as a buttplate. Generally have to plug at least one hole and redrill. Also, you have a very difficult time matching the angle of the heel and toe without the stock.

Bottom line: Send the stock or the entire gun to the gunsmith.

Buy one of the pad fitting/grinding jigs. Midway has free shipping on $49 today.

It's the original pad from a 1986 Beretta o/u and it was perfectly fitted at the factory.

No. There’s no jig or method as far as I know that will come close to matching the results that come from fitting a pad to the stock.

The last time I needed to fit a pad. I mounted it then I took to my local shoe repair shop. Nice guy did it
while I waited. He did an excellent job.

^^^
This…You won’t be happy with the result without sending the stock to a gunsmith.

That being said, if you send it to a gunsmith that doesn’t know what he’s doing regarding grinding/fitting recoil pads, you won’t be happy with the result either.🥴

Unfortunately, there are a lot out there that aren’t very good at grinding pads so do your research before you pick a smith to do the job.🤔

^^^
For this reason, I do most of my own smithing nowadays including recoil pads…

Here are a couple I’ve done recently.
I charge people $100 labor + the price of the pad. But I’m not making a living doing it. A good smith will likely charge more and it’s worth every penny if done right, IMO.


Leftybolt

I've done a few, just work slow. When I get close, I wrap the stock with a couple layers of painters tape and screw the pad on to finish. One I bust through that first layer of tape, I hand sand. Finish up with some murphys oil soap and real fine sandpaper.

As pointed out earlier, using the existing pad as a pattern might get you close but a good fit is questionable.
You can get fairly close using one of the jigs. Putting the new pad on the stock, scribing and grinding. DIfficult to get a really good fit.
For a really good fit you need to mount the pad the carefully finish.
Reasonably, you probably need a belt sander for any of the above options.
Most Beretta OU stocks come off with a 6mm hex head key. Pick out the pad you want, find someone who has experience and skill putting pads on and send them the stock.
Run the numbers, probably the least expensive, most satisfactory alternative

I’d also leave the receiver on the stock while I fit the pad. The less times you install and remove the pad the better. Keeps the screw holes in the wood tight and the slits for the screws in the pad from getting buggered.