A little file work and some frequent measuring should make things fit. One or two thousandths over the size of the hole in the block should be just about right for a tight tap-in fit. If you taper the dipstick tube so the first 2/3 of the block contact area drops in, the last 1/2" or so is all that really needs to fit tight. A snug slip fit and a drop of red LocTite works, too.
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!