I hope the "230" was a typo- - - -the 307 pistons won't work in that one, only the 250. The big block V8 rocker arms work on a 250, but you lose a slight amount of valve lift in the process from 1.75% to 1.7%. Have the machine shop install pushrod guide plates and screw-in rocker studs while they're reworking the head. If you install a cam with slightly better timing and lift, the .05% drop in rocker ratio isn't noticeable.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!