Originally Posted by fbs63
Ross used to make a piston for that in 4.390 bore.


i only see the 1.12ch ross piston in a 4.375 bore in the catalog. I emailed them about some of the 383 pistons in the 1.307ch and to get smaller dish or a 4.29 bore would've made it a custom piston. about $1100.
The OP might be in the situation.

https://www.rosspistons.com/wp-content/uploads/2016/08/RossPistons-Catalog.pdf