If you aren't poor like I am at the moment, JP engineering in SA make custom CAST pistons.
Last price I saw was $660/set, but you'd want to get new rings too.
I could help out with ground work as thy're close to my place and I have some rooted 8.3:1s, 8.7:1 and 9.7:1 pistons to use as samples.
There is another guy looking around at these at the moment too.
Get intouch with:
blueke82
He may have made contact by now, I sent him the details recently of some JP 92mm bore ones that have been made before.