The most equitable division of delegates on a first ballot, if Kasich drops out, would be proportional allocation - but I think the allocation depends only on the discretion of the Ohio state GOP.
Trump 13%
Cruz 13%
All delegates bound on the first round. Might it be that 13% wouldn't be enough to apportion any delegates to Cruz? Meanwhile, if Kasich can get in and stay in, can he give those delegates to Cruz?
In OH, Trump is a lot more popular than the result indicates. I don't know how that would play in the state. The delegate process is impossible, so it's probably all insiders who became delegates.