slantsix valve adjust

I set mine to .013/.023 at ambient temp, probably 65 to 75 *F. The hot-lash is perfect on mine when I do it this way, and I don't have to be in a hurry.

Also keep oi mind that slantys get neglected so bad that the rocker arms tend to get grooves worn into them by the scrubbing action of the stems. So the feelers you use will have to fit into the grooves. That means narrow tips less than the width of the stems.
If you use regular feelers, the lash will end up much too big.
To do a cold set, with the engine not running, there are two methods. I prefer doing each cylinder by itself and following the firing order.I start with the plugs out and whatever piston is close to TDC on the compression stroke.Both valves are closed so the cam is on the base circle.Then I rotate that piston to TDC. The easiest way I have found ,to determine TDC close enough to lash valves, is to have a compression tester hose screwed into the plug-hole, and the other end in my mouth. As long as the piston is coming up it blows my lips apart, but as soon as it goes down the other side, it wants to suck my spit out. So when it stops doing either, then it's ready to be adjusted.
The firing order is 1-5-3-6-2-4.
Then I proceed to the next cylinder in the firing order, which will be along in 120*, or 1/3 of a revolution. Again the hose in the plug hole gets TDC close enough for adjusting the valves.
Using this method means you don't have to be super accurate in finding a certain crank position. I'm sure that if you are within 1/8 turn of TDC it will be fine. 1/8th turn is 22.5 degrees . But I guarantee the pressure-suction method will get you a lot closer than that, probably within 5 degrees either way, if you are sloppy about it.
After the engine is all buttoned up. you will probably not know if the lash is too loose.
But you will know right away if it is too tight. The engine will not start normally (with a click of the key), and it will idle roughly (only 3-power pulses per revolution, and the power will decrease as the engine comes up to temp.
On mine I have found that an accurate hot intake lash of .010 is too tight. And an accurate hot exhaust lash of .013 is also too tight. If you accidentally did both at the same time, well you are looking at a do-over right away,lol.The engine runs terrible, and the hot-start also is terrible.
Good luck
PS, remember to use the narrow feeler blades, and like said;one atta time, and I put a key-ring on mine. It's amazing how slippery they can get.Actually I cheat; I put the two feelers that I am gonna use, on the same key ring, allowing the second one to become the handle,lol.