Is there a adapter thats sold that can mate a trans other than a "bop" to a 455 olds engine?

 

Yes there are adapter plates for other GM transmissions they add about 1/2" to the length of the transmission

 

Just to be clear, the adapters that are commonly sold allow the BOP and Chevy pattern transmissions to be interchanged. This lets you mate a 700R4 to an Olds, for example (though I'd still go with a built 200-4R). Note that the dowel pins and bottom two bolts are the same for these two bolt patterns.

 

IF you go with a 200 4R it will have to be built to withstand the torque of a 455. Go to the Turbo Buick forum and get ahold of Brian Hofer. He is a 200 4R guru. The adapters are readily available on Summit. One company that makes them is TransDapt.