As 1Ton tommy said you would eventually run out of adjustment on the rocker arms.
Maybe that's why a stovebolt intake valve is a half inch tall above the keepers? Every valve grinding machine I've ever used in the past 60+ years has had a fixture for shortening the valve stems accurately. On hydraulic lifter engines with non-adjustable rocker arms, adjusting the stem length to get the proper preload on the lifters was always part of a good valve job. Doing stuff like that is what separates the pros from the shade tree wrench jockeys.
Another option to correct the valve geometry when milling a 54-55 head to get 848 compression would be to put a 3/32" (.093) shim between the rocker shaft stands and the head, and use a hardened steel lash cap on top of the exhaust valves.
Most 235s and 261s use the same valves. The only exception I know of was the 1950-53 spray-oiler 235s used with Powerglide transmission applications- - - -they used a bigger intake valve diameter- - - -1.94 inches. The later model 235 and 261 engines can be fitted with the bigger intakes.
Jerry
