The 1st stage looks like a srb3205 or srb 3305. Either way, a hard to kill 1st stage.
The Shadow sux...just sayin'. Sell that off.
Pick up an adjustable first stage for your primary. Use the other Oasis/Blizzard 2nd stage as your second. These seconds are good and can be tuned just right, but I find myself re-tuning them every so often. I use one on my bailout, slightly de-tuned to prevent free flow.
I own [ed] A LOT of Sherwoods, and use them a lot as well. Their first stages are easily rebuilt. Kits are dirt cheap and can be had easily. I'm cheap so, I make my own kits from supplies at McMaster-Carr.
I have 2 that I have not changed the HP seat in about 5 years. I dive just about every weekend too.
There are those that claim that these are "shallow water" regulators. Not sure where this bs started. But, as far as recreational diving, you won't notice the difference from one of these from a Scubapro MK20.
Also, a tip to prevent sea water entry into the dry bleed system.
After your dive, soak the reg charged to a tank. I use a cooler and my bailout bottle. After soaking, remove and turn tank valve off. Do not purge the reg...the dry bleed system will discharge the air and dry out the bleed system. This will take a bit mind you. Salt water can get into the system if not cleaned/purged and will kill the little filter that is on the piston. Ask me how I know.
Have fun with your new acquisition!