I discovered that the aftermarket chrome dipsticks for FORD SMALLBLOCK V8 sold by your local Advance or AutoZone or O'Reilly had the right diameter tube to fit my 250. Had to cut the stick & recalibrate it, though.
I was thinking that they might work. Glad that somebody could verify before I went out and spent the money only to find out it wouldn't. Thanks, you saved me a lot of time.