Panope is a sister ship to the OP's boat, hull built in the same yard.
When she was schooner rigged (prior to my modifying to sloop), there where eight chainplates (four per side) spread along the gunwhale. This low aspect rig, combined with a somewhat tender
hull, means the rig loads are far lighter than comparable sized modern boats. We used 1/4" galvanized wire. One wire to each plate.
The point of mentioning the above, is that it trivial to size chainplates large enough to eliminate concerns about strength, fatigue and longevity.
Also, these boats are built with a somewhat "industrial" flair. Therefore, oversized, chunky looking components will fit right in
As mentioned above, forget about the bolts. Just weld.
The stainless bushing (where the shroud
attaches) is a nice touch. An alternate to the pressed "interference fit" that estarzinger mentioned, is to first chamfer the hole at both ends, then secure a loose fitting bushing by battering (or clamping) cone shaped mandrels, thus expanding the lips of the bushing into the chamfers.
That said, when I built new chainplates, I did not bother with a bushing. I use industrial, galvanized turnbuckles (the ones with crude, lumpy pins) in an oversize chainplate hole. My new chainplates (just one per side) are now 1 inch thick by 6 inches wide (where they are welded). This crazy big for a 7 ton boat. They will last forever.