I researched this more on hardcoresledder.com. All the posts I saw people say there are no upgrades for the 700, only the 800's.
Is there is a reason why you want the stainless ones? Topic 1 Topic 2 Topic 3
The aluminum ones can fail due to heat, when they go it takes the top end out. That is why they updated to stainless. Not sure why they would only update the 800.
For my application im running a turbo, with the added heat just seems like cheap insurance.
So looks like no luck with stainless. Anyone know if there is a part number that is a kit for the 700(new valve, bellow, spring, gasket)? I haven't found anything.