273 to 360 swap. same converter?

That seems like it only would be a problem if the flexplate became loose somehow. or the converter bolts were loose. in that case nothing would save the bushing or the seal. the converter bolts are the reason it stays in one place. I'll get the adapter ring anyway I was just curious about it's purpose. If I was going to race the car I would worry about it. But, it's going to be a daily driver.
wrong! the pilot is what centers the convertor to the crank. the bolts are just there to hold it in place.