Hi Randy & welcome to the forum!
Well you aren't going to get very far going with 8-32 dies, because the thread size is 8-36 x 3/8".
The hex head wrench size is 9/64".
Blued are relatively easy to find, stainless is another matter mostly special order.
Gas block screws are running between $1 & $2 depending where you get them + shipping.
I have purchased a mass quantity and have them available for our members for minimal cost. I wouldn't try to chase the threads on a Stainless screw, because of "galling" they may still be rough.
I have already done the leg work on this, much cheaper than buying dies. Also ain't an easy size die to find. Save you some work & $.
link to the for sale parts Gas Block Screws
I also have a harbor freight 1/4" drive inch lb torque wrench & it does OK, but I had a hard time finding a 9/64" hex end socket to fit. The ones I found were to short to reach the back two screws. So I took an old 1/4" drive, 1/4" socket, cut off the long part of a 9/64" hex wrench and used JB weld to make my own, works good.
Here is some "canned" info about the gas block screws.
One of the biggest reasons to use new screws when taking apart the gas block is that Ruger “stakes” the screws at the factory to keep them in place. They do that by taking a sharp punch and putting an indent into both the threads, in the gas block screw, and in the top of the gas block, this locks the screw to the block. When removing the screw it will have a sharp spot, or burr, on it from the staking that will impact and damage the threads slightly as it's taken out. If you continually remove and replace staked gas block screws, without removing the burr from staking, the burr on the screw can damage the threads in the upper part of the gas block. Worse yet, if you replace the upper gas block with an aluminum scout mount, such as an Amega or Ultimak, and reuse a staked screw the sharp part of the staked screw can destroy the threads. If you do have to reuse a previously staked screw I would suggest trying to get the burr from the staking off the threads of the gas block screw before reusing. Also be aware that on a stainless steel mini there is an added reason to use new screws, stainless steel has a tendency towards something called "galling". That is when two pieces of stainless steel molecularly bond to each other by being in contact with each other, when the two pieces are separated they have a rough surface, reusing stainless steel screws can damage the threads if rough from galling. The mini gas block is a factory replacement item only, which means sending the mini back to Ruger to repair it or replace it, so you really don't want to mess up the threads in the gas block, especially if testing gas bushings and taking apart your gas block repeatedly. For testing no need to stake the screw until you decide on a size. You can use locktite if you want to lock the gas block screws down without staking. If you do have to reuse a previously staked screw I would suggest trying to get the burr from the staking off the threads of the gas block screw before reusing, if at all possible.
The engineering torque spec for that size screw in Stainless steel is 22 inch lbs, I have done mine to 30 inch lbs, others have gone higher. I have seen one mini with a cracked & broken upper gas block so I don't subscribe to the "gorilla" tight, more is better method. I saw that mini after the fact & have no idea how it got broken.
PM me if your interested & I'll send you the rest of the "canned" info & contact info.
Best O' Luck,