In my case ride height is set by the rules of the category, for 2B Marque sports:
RIDE HEIGHT All fully sprung parts of the car must clear the ground when both tyres on the same side of the vehicle are deflated.
And also what the suspension dictates in terms of ride height when set up
I would get the suspension sorted first to see where you are and then work out the rest from that to then put in bash plates or go dry sump to minimise the oil pan under the block
See if this seller on Gumtree can help you out : https://www.gumtree.com.au/s-ad/caboolture-south/collectables/datsun-240z-and-260z-original-assorted-parts/1192338713
A long way away from you but seems to have some good parts.