360 engine vibration at ~3000rpm

Gents,
I feel bad about not closing this thread out earlier, but here it is ..finally. The noise was from a BAD internal bearing of some type. I (& my local gear-head friends)expect a lower crank bearing due to nature and the sound as it became worse(2nd guess is a cam bearing).
During the last few times I drove the car in Oct and early November, the "knocking" noise became more pronounced and started at lower RPMs even when the motor was not under a load (like accelerating or pulling up a hill, etc..). Took it by a reputable/trusted engine shop and it was also their opinion that had it was an "internal" bearing failure. So,...
My pals and I pulled the engine a few weeks ago and delivered to a machine ship in Louisville Ky (Auburndale auto parts & machine shop) the week prior to T-giving. Plan is to: a) open up engine and determine cause of knock, b) if block(date stamped to be a 1970 block) is "good", rebuild as a 408 stroker engine and use the existing heads if they "check out"(may shift to alum. heads if mine are "not good"), c) deliver engine to Dale Meers engine shop in Buffalo Ky (about 20 miles fm my home) to break in Cam and "tune engine, d) put everything back together including TTI shorty headers I ordered ~2 weeks ago,..etc..etc...(Hope to be road-testing sometime in early 2021).
more to follow...-Scott