Are all 273 V8's the same?

The "T-Flight Patty" name comes to mind of the centering ring to make a small snout fit a 68 crank, but its only a 1/8 wall ring, nd it can be made (really!) by chopping up a few 1/8 drill bits and tacking them together in a ring pattern. Simce the crank and convertor turn as a unit, there is no bearing surface to worry about, its just to center the slightly floating converter. I actually ran a 65 cable trans behind a 340 for about 4 months without a ring (unknown one was needed) before it started to vibrate a little, then it kicked out a corner of the flex plate. After I heard this I limped it home and took the trans down and found all 4 ears of the flex plate were cracked, 3 of them fell out when I unbolted them from the converter before taking the trans bell bolts out. Lesson learned. In went a 340 and a 68 904 and a 8 3/4 with a new driveshaft.

PS>> my barn find 4/1/65 production date '65 'S' had 4bbl quench 2 relief pistons in it.