I seem to be another victim of the dreaded hydraulic lifter issue.
My 65 273 235hp has 600 miles on a full rebuild.
I swapped the solid cam for a General Kinetics cam with hydraulic lifters. Now the rockers are loose she is a'knockin and rattling.
I can swap out the lifters quick enough but to what? another set that will fail?
Aside from tearing it apart again for a new solid cam and lifter set, what other options do I have?
solid lifters on the hyd cam? better set of lifters, like anti-pump up?

Did you change out pushrods also?

YES pushrods are different length between solids and hyd. However the pushrods do not have holes in the ends.
As part of this stressful adventure I noticed the oil pressure is lower than normal when hot. Hot oil pressure is 40 at 2000rpm.

I would look at the cam.I bet you lost a lobe or 2 and the shrapnal went through the oil pump causing your low oil pressure. Been there done that!Hope you have better luck than I did!Good luck!

Assuming you find wiped lobes/lifters...next time, with the intake off and everything mocked up, turn the engine over and make sure the lifters are rotating. If they aren't, it will do it again.

Over the last few years I've seen several sets of hydraulic lifters that had insufficient crown and would not rotate....pair that up with the additive-depleted modern oils, which is a whole other topic, and you've got a recepie for a mess.

Cams have been made basically the same for eons, but lifters have not, unfortunately.

say it aint so..
I did pull a couple of lifters..
look nice no wear but I could push the middle in by hand on one.
ran the car with valve covers off, all the rockers seem to actuate.
idle is good, after adjusting all the valves but after running it around a bit the noise returns and the rockers are loose again.

I do need to check lock nuts to see if they are backing off, but they seem tight.

would bad, collapsed lifters affect oil pressure?