If you know the spring rate you can calculate the new load.
So... 1.70-1.67 is .030 X 402 is about 12 pounds.
That would make you about 127 on the seat, give or take because unless you verify the numbers with a spring tester you are still operating on faith that the spring is what the manufacturer says it is.
How wide is the sweep? I'm assuming 273 rockers correct? If so, with that much lift there is no way the geometry is right. Can't be. The shafts have to come up and move away from the valve.
You can't change one or more parts of the equation without correcting for it. That means the stand height and position relative to the valve, stem height, net lift, geometry of the rocker itself and I'm probably forgetting something.
IOW's, when Chrysler developed that system, it was for a certain stem height, with a known net lift using that rocker. You have changed the lift by a good amount. Now, that means you need to change the position of the shaft to get everything back where it needs to be.
There are two and only two ways to fix that. Use a kit from Mike or mill the stands off and use blocks and shafts with offset holes so you can alter the position of the shaft.
I never bought into the half lift deal, especially with shaft rockers. You want the sweep as narrow as you can get it.
