Talk to a few piston manufacturers,
If you're getting the rods made, see if you can get the even longer with the pin moved a little higher.
That is instead of an installed or compression height of 30mm, why not use a modern box section piston with a C/H of say 27mm...
This will help you get more top end & allow you to use a longer stroke without compromsing rod ratio.
Well, that's my 5 cents