The later 70-SS spindle should work, 56mm between bearing shoulders, 28mm left side, 31.5mm right side, overall length 115.5mm. Use the later thick rifled cups. Should check whether needs 1/4" or 3/16" ball bearings.
The older 70-SS-120 +1, 1.5 should also work, similar dimensions.
Show us pics of what you currently have so we can see the threading, cup thickness, and bearings that are already in there. Can you measure the diameter of the bearings using a pair of digital calipers?
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