Strange combo

I think my brothers 340, is an old school stroker, think his comes out to 357ci. Ran it in a IMCA Modified and when rumors of someone claiming the engine, he switched to Chevy. He didn't want to give it up for $350. He gave it to me, I asked what it would take to run on pump gas and he said custom pistons probably about $700, I rebuilt the 273 instead. I too would like to build a 273 stroker.