Has anybody successfully done a brake upgrade using a booster other than a S-10’s? Have heard it’s slightly better but still has similar pedal feel. Looking for softer feel for spouse that’s comparable to an early 2000’s vehicle.

Don’t know where you got that info from. The s10 booster reduces the pedal pressure by 50% ! Definitely makes it feel like a 2000s car. And it’s the same whether you just swap the booster or do a brake upgrade as well.

Could be your Booster is "bad," have vac problems or maybe both.
Examples:
84-86 Fiero and other cars have a vac filter in engine bay like to plug. OE is Metal Can on firewall.
All have a vac check valve that leaks/plug internally after 20-30 years. 84-86 has different valve then 87+ because 87+ uses bigger vac line.
Booster could have 1 of 2 diaphragms fail causing harder pedal.

Could be you have other brake problems causing hard pedal.
Example: MC w/ iffy QT valve can cause hard pedal.

See my Cave, Brake Service, Quick Take-up notes and rest of section.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 06-25-2020).]

When I did the upgrade, I used the kit from Rodney's store, and the recomended booster I got from Summit racing. I prefer this setup as you might need a replacement booster in the future ( I did), and it was easy to purchase a replacement.

https://www.summitracing.co.../chevrolet/year/1993
http://rodneydickman.com/pr....php?products_id=350

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'87 GT , '00 3800 Series II SC, 4t65e, Vue Power Steering. (SOLD)

the GOOD S10 booster on a "properly working" stock fiero brake system, with very little pressure it could almost throw you into the dash. if it doesn't, something is wrong.