The Mini 14 is over gassed by design so that it will run with pretty much anything.
One of the frequent complaints from Mini-14 owners is that they'll throw brass 20-30 ft with some loads. However, what some Mini-14 owners don't know is that the early Mini-14 (like your 184 series Mini-14) used a plunger ejector, while the later Ranch Rifles and Mini 14s have the ejector incorporated into the bolt stop. It's the later Mini 14s that will throw brass into the next county. You won't see much difference in ejection if you install a smaller gas bushing.
Most Mini-14s will run with most loads with an .045" bushing, so it's a pretty safe bet, while some will start to short stroke with some loads with a .040" bushing. The differences include the specific load being used, as well as things like wear on the gas pipe and lubrication of the slide.
The other common addition to an older Mini-14 is a shock buffer - either a 1911 buffer, or one made for a Mini-14. It'll chew up and spit out the 1911 bushing in a couple hundred rounds while the larger Mini-14 bushing will last a couple thousand.
Some shooters think the shock buffer gives it a smoother feel when shooting it, and some shooters feel the combination of a smaller gas port bushing and a shock buffer helps improve accuracy, although the greatest improvement for a thin barrel Mini-14 is an Accu Strut and a Choate flash hider. Both my 184 series Mini 14 and my 187 series Ranch Rifle will turn in 1.5 MOA 5 shot groups.