The factory corvette 327 was at 375 rated horses in the early 60's.. My cousin had a contract building farm truck beds for the dealer and used to get chevy stuff at cost. he would build up a crate 375 horse long block with 2 fours, drive it for 6 months or a year then sell it for a profit and build another one either for his 55 post or anglia 2 door. both very fast.