I had this EXACT same 365hp rag top in 1965. I bought for $4,300 at Norgate Chevrolet on Long Island. That car was exceptionally fast. When the 396 was release later I the year, I would always street race against them. The 365 would jump the the big block but the 396 would slowly grab me above 70 mph. The small blocks did handle MUCH better than the nose heavy big blocks.
Side exhausts alway gave me migraine headaches. Besides, he under car exhaust actually produces MORE horsepower that the efficient side exhaust stystem.