I have Weaver top mount base pairs 48471 on my Rio. Made for Marlin 336. Have to use the Rossi screws. Also use Weaver quad lock scope rings.I found the screws in the bag with the TSS keys.
Turns out the Rossi uses smaller diameter screws for the scope base.
The spacing of the Rossi holes is identical to both my Glenfield 36G and Marlin 336RC.
So, Marlin stuff might still work by using the Rossi screws, depending on how the screw is seated.