Jim,
I think the typical 12 volt starter in good condition will not draw anymore than 150 amps. Because your engine isn't running 11:1 pop up pistons, a average battery and a average starter would do just fine.
I thought most off-the-shelf 12 volt batteries were in the 400 CCA or CA spectrum...maybe not! Keep in mind it's not only the cranking juice you're after, but the capacity for all your fancy electric do-dads.
Your stock battery box should hold a battery that is more than adequate for your nice new engine in my unprofessional guesstimation.
Stuart
