Measuring pushrod length

I am trying to find the correct pushrod length on an engine I am freshening up.
It has a Crower hydraulic flat tappet camshaft of unknown duration lift etc.
CHI 2v heads on a stoke stroke 351c.
3 coils for valve springs. Proform 1.73 ratio roller rocker arms, Manley valve guides.
The pushrod are 3/8" 8.4 length and when rotating them, some are slightly bent.
They are not centered on the valve, some maybe 30% contact, I will cut / modify the guides so they will.
Watching the roller tip and viewing the wear marks on the valves, they seem too short, just rubbing on the intake side.
I have a CompCam pushrod length checker and a length of 8.7 will bring the tip rubbing the intake side and into the centre.
The question I have is, that the hydraulic lifters have 'collapsed' so I will not be getting a true lift at the valve.
This will change when the lifters have filled with oil, at max lift the contact point I am trying to measure.
I do not want to remove the heads or remove the existing valve springs to fit lighter ones.
Is it okay to measure the amount the hydraulic lifter is collapsing and extend the pushrod length checker that amount?
I understand I need to be careful about valve contact.
Other suggestions?

Does 8.7" length seem a lot?
If I use this length of pushrod the polylock is only gripping about 4 turns on the stud, is this enough?

At least one of the rocker studs is bent also so I want to replace them. I do not know the manufacturer.
Is there a longer rocker stud available so I do not need to shim them up to get more threads in the polylock?
I have stock factory screw in studs that I compared these to and they are about the same length.