Obtain as much Velocity Force values Koni would provide over email.
Stock 88 spring rates.
205 lb/in front, 147 lb/in rear.
The Corvette 8040-1019 and GM A Body 8040-1087 are only 10mm longer but have the same stroke.
Velocity Forces @Full Soft (Rebound and compression, where available, approximately double at full hard)
Newton to lbs converstion N * .2248
Fronts
Fiero Front Shocks 8040 1027 (84-87)
5in/sec 200N static compress 900N-1800N rebound
13in/sec 300N static compress 1350N-2700N rebound
Fiero Front Shocks 8040 1092 (88)
Discontinued
5in/sec 420N static compress 750N-1500N rebound
13in/sec 750N static compress 1200N-2400N rebound
Possible Front Replacements
Corvette 8040 1019
5in/sec 420 static compress 750N-1500N rebound
13in/sec 750 static compress 1300-2600N rebound
GM A body 8040 1087
5in/sec 430N static compress 780N-1560N rebound
13in/sec 900N static compress 1250N-2500N rebound
Surprisingly the 1092's are almost identical to the 1019's and 1087's. I ordered up a set of the 1092's and 1087s, as the 1087's have the same cross bar and bushing size as the 1092's.
Koni 80-2859Sport would probably also fit similarly to the Koni 30 Series setup from WestCoastFiero but perhaps with no eyelet to pin modification
Rear
Fiero Rear Struts 8741 1063
Discontinued
5in/sec 230N static compress 560N-1120N rebound
13in/sec 350N static compress 850N-1700N rebound
Possible Rear Replacements
Yellow Dual Adjustable Strut inserts 8611 XXXX
5in/sec 280N-560N Compress 750N-1500N rebound
13in/sec 400N-800N Compress 1150N-2300N rebound
Yellow Single Adjustable Strut inserts 8610 XXXX
5in/sec 600N static compress 750N-1500N rebound
13in/sec 850N static compress 1250N-2500N rebound
This is where it get's a bit tricky for a koni rear strut equivalent. As can be seen you can get close to the original Fiero Koni rear with the 8611, however, the 8611's go for about 350$+ a shock... that's a deal if you're looking for a double adjustable rear strut for autocross/hpde etc..but not so much if you're looking for a comparable strut to the 1063 at a similar price point. I'd be interested to know the force velocity's of the KYB rear struts.
The 8610's are near the same price point but the static compression numbers are probably too high for a daily driver...
So Will, it looks like the 1019 and 1087 effectively are indeed koni single adjustable "yellow's" for the fiero as you theorized some time ago on within a post on OE.
And look to be suited to running 725/475 spring rate combo or even a little higher at roughly 100$ a shock. But unfortunately someone would be in for a "shock" expecting anywhere near an OE or koni 1027 ride.
Edit: duh.. I was looking up the 8040 1027 which are for the 84-87 front koni's, obtained the 8040-1092 88 front koni force velocity's and they are almost identical to the C3 Corvette koni fronts
Furthermore, Koni does make a coilover conversion for these 80.0000.1 (can run both 2.25 and 2.5" springs) unfortunately a sleeve retainer ring will have to welded onto these 8040's which koni says requires a tear down but I've found a couple of koni yellow owners who have done the same but with slow, intermittent tack welds to keep the shock body cool enough and prevent and internal damage.