You probably need to source the fork from eBay ... the option of a 'good' 1" suspension fork is probably an old Rock Shox Judy or a
presumably-made-for-Specialized-by-Rock-Shox fork.
The department store MTBs may have forks with 1" steerers ...
Regardless, a 1" suspension fork will probably have limited utility because its travel will be very limited regardless of vintage ...
FWIW. Having once given this very situation more consideration than I possibly should have, if you want a more contemporary fork, then the better option may be to buy the suspension fork whose specs suit your riding requirements & then replace the 1 1/8" steerer with a 1" steerer ...
THAT may-or-may-not be a daunting undertaking ...
- some steerers are integrated into the shoulder
- some steerers are held in place with pinch bolts
In the former case, if you can't extract the steerer without damaging the shoulder then you could
amputate the steerer and then bond ([COLOR= #808080]and "pin"[/COLOR]) a 1" steerer inside the resultant hole ...
In the latter case, you may have to fabricate a steerer using 1" tubing ...
In both cases, you will probably want to bond a collar of some sort ([COLOR= #808080]
e.g., brass strip wrapped around the tubing[/COLOR]) at the base of the steerer for the headset race.
If you aren't a purist & the frame has limited historical ([COLOR= #808080]
aka monetary[/COLOR]) value, the you could have a frame builder (or, you could DIY) replace the head tube with one which will accept a 1 1/8" steerer.
Personally, I would just opt for a rigid fork ...
If need be, I would just use an 'old' ROAD fork ... without checking, I reckon that a BMX brake caliper ([COLOR= #808080]the reach is in the
95mm range[/COLOR]) might work ([COLOR= #808080]or, be necessary![/COLOR]), or not.