Pre-Accu-stock Savage 220 Slug Gun DIY BOTW build

Okay pardon my naiveite in the world of Savage actions and bottom metal inletting. Let me set the stage for how I got here and what I'm trying to accomplish:

1. I've missed a few Booner's with my 220.
2. I'm working to eliminate any doubt in the Indian's mind that it is the arrows.
3. I have a 1st gen 220 slug gun with the top bolt release and shorter than accu-stock bottom metal.
4. Have mistakenly ordered a Boyd's stock inlet for the longer/updated accu-stock 220.

Best of the West sells a Savage 220 that utilizes a Accurate-Mags DBM bottom metal and I'm wondering how they accomplish this. I'm under the impression that the 220 is built on a long action 110? Is the action screw spacing the same between short to long action?

Given that I have a Boyd's stock inlet for the new accu-stock bottom metal is there any way to use this with the older generation 220 action? Any assistance would be greatly appreciated!