The mono-blocks i have here are for the older ruger red labels,20 years ago we made o/u double rifles for these, this i will not do because we learned that you need to build new firing pins and bushings so you don't start punching holes in your primers and to reinforce the recoil plate because of receiver cracking in the 444 marlin barrel sets.
As for shotgun barrel sets,the 20 gauge receiver is a good shape and size for a 3 barrel set,20,28 and 410.the 28 and 410 barrels sets are 28 inch barrels,and the 20 is 30 or 32 inch fixed choke or we install briley tubes.
For a barrel set it is $1200.00 which includes everything and we will set the POI at what you want.
Rib height can be flat or the tallest rib we do is 1 1/2 inches,we also can taper the rib.
Widths are 5/16 to 1/2 inch,oval posts or round posts,the round posts are used on model 42 winchesters and are 1/2 tall.
Monday i am going over to pick up an older 20 gauge red label and i will check it out.