I'd guess it depends on which credit-only hopper unit you had.
early games like the 847-1 had different frame parts on the hopper unit and had the score motor on the hopper.
later games like the 910 moved the score motor into the machine and the hopper frame parts were the standard ones with a front plate instead of the coin parts.
your pic is in between what I've seen diagrams for in the bally 500, 1100 and 1100 supplement manuals. You have the score motor on the unit but also more of the standard frame bracket pieces.
in any case, if you just have a donor coin hopper unit, you can almost certainly just transfer the payout counter unit to it and make it work. You may or may not need to transfer the payout relay.
if you have the standard frame credit-only hopper, you should be able to bolt on the coin hopper parts in existing holes.
I assume there's no safety circuits for detecting issues with the hopper in the credit-only machine, so you'd need to decide if you care about that.
is the coin diverter still on the credit-only games so you can make coins go into the hopper?