I played the SNES version and beat it by heavily using save states and load states lol. nothing special about what I am doing.Gradius 3 is incredibly difficult. Did you play it on that new PS5 Gradius Collection that quietly dropped in August? That has the best version, the arcade version. If not I'd recommend picking that up and playing the other Gradiuses.
If emulating, SNES has Space Megaforce (insanely good shooter), Super R-Type, Axelay, UN Squadron. If you want something super difficult, and I mean ridiculous, there's R-Type III.
Two extremely good and extremely obscure/cult classics that might require a little more effort to get running: Turbografx-16 has Blazing Lazers, PS1 has Gradius Gaiden.
Einhander is the other one on PS1 that I'd recommend. I played the PS2 variants of Gradius and R-Type and don't remember either making any real impact.
I will check those out man. thanks!