Clutch noise?

Finally got to the point today where I could start the sbc with sm465 and 205 that have installed in my 68 715. No drive shafts yet and up on jack stands still. Good oil pressure but have noise that almost sounds like a rod knock (but pretty sure it isn't doesn't because if any thing it gets lighter with more rpms do). New clutch, throwout and pressure plate but all new to this engine. Guess I'll pull tranny and tcase but thought I'd ask if you guys had any ideas to check before I do? Thanks that 265 is heavy.
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Check to make sure one of the tranny mounting bolts is not too long and hitting the flywheel or pressures plate.

will do thanks

Is it a double knock? If so it may be a wrist pin. They can sometimes knock at idle then go away under light acceleration. Try pulling plug wires at idle to see if it goes away. Removing the spark at each cylinder removes the load from the piston and can make the knock go away temporarily.

Also, are you running forged pistons? They can knock a bit when cold until the engine comes up to operating temperature.

One last thing: The cam thrust on the front of the block. If there is a bit too much play in it, it can also give a knock too. They seem to be more pronounced when cold as well.

slightly depress the clutch pedel if its the clutch the noise will go away. you dont have the disc in backwards do you JMO
ALSO USE A BROOM HANDLE AS A LISTENING STICK.
ron