I would suggest you measure the installed height of the valve stems, and then read up on the cam, lifters and rocker arms that you have installed. Sometimes the new cam can require a specific combination of rocker arms, supports, springs, retainers, washers, valves, and even grinding of the top of the valve guide.
What that translates to in English: You can't just buy a bunch of aftermarket parts and expect that they will play well together. Specific combinations may be required.
I do not have any particular company in mind when I make the statement. Just general experience.
p.s. the springs you installed may be too strong, or when fully compressed, the valve spring coils end up touching each other, thus being a hard stop which bends the pushrod.
tom

 

If you replace the rockers you'd best match the shaft to them. Had trouble with this myself. the advantage of an adjustable rocker for me is so I can get it dialed in where I want it and not have to fool around with changing push rods until its perfect. True you won't get much power gain unless you go with a solid roller cam, but I just like the set up so I can adjust it to suit me

 

Why does Ford have (3) different pushrod lengths for the 390 engine?
I have a 390 with a Sig Erson E240030 Hydraulic cam; it is a mild "RV" cam with 0.458" Intake lift and 0.484" Exhaust lift
I am going to do the "Holley Jet" oil gallery restrictor process, so I thought I would check all the pushrods while I had the rocker arms off.
O'Reily auto parts shows three lengths; 9.560", 9.621" and 9.680"; These are "non-adjustable" rocker arms for Hydraulic lifters, so why 3 pushrod lengths?

 

Back when the engine was designed, there was more tolerance in machining, leading to 'stackups' of tolerance that could vary the geometry of the valve train. Additionally, when the valves are seated, they can end up having different installed heights. The pushrods are available to center the hydraulic valve lifter piston in its travel given the various differences. To determine the proper pushrod length, the lifter is collapsed, and the clearance is measured to figure out the correct length. If it is to small, a shorter pushrod is indicated, etc.
When a valve job is done, and they were done more frequently back then, the valve train length was shortened by the amount taken off the seats in the head and the valve tulip. Again, measuring and fitting the pushrod was the only way to get proper clearance.
tom