i cant remember exactly what sized i used for mine, but it should be real close to that. i'll let you know when i get home in a few hrs, if it works for you i can ship it no prob.
by the way, to get a straight hole, can take a side cover off so you have a flat side 90* to the hole, i put mine on a bridgeport and with some parrallel blocks got her nice and flat, then clamped the engine down, then lined the hole up by eye and fine tweaked taking a couple thousandths depth drill to make sure drill was centered in hole, then punched right thru.
e-z.
theres no need for cobalt, carbide, or any coated tip on the drill. it will punch thru that cast aluminum like butter, plus youre only taking like .060 off each side of the existing hole.