Any V8 you put in there will look a little different than the stock 235 straight six, so I wouldn't worry about stock appearance. I think the 265 V8 was an option in 57 or 58. They were a year earlier in the GMC with a 347 cubic inch Pontiac engine. You may be able to clear your axle with a 4X4 oil pan to fit your engine. I'm sticking wiht the old 235 and accepting a slower life style. (55 second series w/early Napco upfit)
good luck and bring your patience!
Pete
