Let me try it this way...
The LYB PASS CAR and HT engine mounting is different isn't it, just as the PASS CAR and TRUCK FYB? How is the 368 mounted in your 57 MERC, like was done with (?)
as the 58 LINC/BIRD 430?
There are no side support pads on the 368 block?
I have a '57 MERC SHOP MANUAL somewhere, just too lazy to dig it out.
I understand about the specialty bell but to say there was not one available is misleading (referring to a separate post by another member within the same thread).
(Besides, you need your cage rattled as you haven't been around for awhile...
)