TimSS

I have an iron headed 350 LT 1 in my 62 Nova , got all the nice bolt ons , bigger cam , some head work , best running 350 I have ever had. My problem is that it started making a squeaking sound almost sounds like it is coming from the valvetrain. I had done a search for that noise and it had come up on the Impala site that the iron head cars needed a different exhaust valve seal , which I guess what that would mean is the exhaust guide was running dry because of the seal being to positive which somewhat made sense to me . I had installed LT4 valve seals when I changed the springs out and the cam . So I went on and installed the different part # seals on the exhaust valves , fired it up drove about 20 or so miles and the squeak was gone.The next day I took it to a car show about a 40 mile drive and on the way home it started the squeak again. The upper end is oiling fine , I am running 1.6 roller tip rockers and all of the exhaust ones I pulled off the bearing tip and ball assembly were all well lubed . I am not quite sure which direction to head with this before I start tearing more apart , any one else had this ? I wonder if one of the roller lifters could be going south ? Any Help would be most appreciated ......Tim