No plan B brass wont work. Plan A failed beat them up to much.
Ayuh,.... Why won't plan B work,..??
Core plugs are sold by material, 'n diameter,....
Goin' by the link ya posted, ya need 1, 3/8" core plugs, in either brass or ssteel,....
I believe the set AD linked are block core plugs, not manifold core plugs,...
Bein' 1, 5/8", yer right, those won't fit,...
Search somebody like dorman for 1, 3/8" brass/ ssteel core plug/ freeze plugs, 'n you'll find what ya need, cheaply, by the piece,...
For future reference, SoP to remove a core plug is to tap it in, in one spot to tip it, 'n then pull it out with pliers,....
Not that I'd reuse one anyways,.....