picked up a 340 long block w/out specs

While true, 340 blocks are a bit of a rarity now and need to be preserved as much as possible. To answer questions, I’d degree out the cam timing events with a dial indicator and a 360 degree tape on the balancer. A compression test to check cranking pressure and some fancy math from victory library or the like and you could get a reasonably close use of your actual compression and cam specs. But not knowing the history and if it had been run it usually isn’t a bad idea to check out the rod bearings because they do take a beating in a blower motor, especially if detonation has occurred. Even when everything is right, a blower motor will see detonation at some point in its run cycle, unless it has been fed a constant diet of expensive race fuel.