Get some calipers and measure the lobes, short and long side, subtract and multiply by 1.5. That should be a close guess at lift.
If the old cam is a 285, I'd bet it's similar to the old 230-480 camshaft. Most of the aftermarket had cams in the 230-235 range and 475-485 lift. A Comp 268 has the same basic lift with a little less duration at .050 which should settle down the idle a bit.
I think you should have done other things to make what you have work using a degree wheel/dial indicator and getting more initial timing on it. You are in too deep now to go back.
