Lots of exhaust smoke. Head gasket? (with video)
 

Cranked with timing totally off for fairly long time. Once corrected lots of smoke out exhaust about ~30secs after starting and significantly more with throttle. Definite HG or is this a sign of more damage? Planning to do a block test but with this much smoke perhaps it's dead obvious to someone with more experience.

Video of exhaust under idle: https://imgur.com/a/t4bXR

Background: I've been burning oil and was doing my valve stem seals. I added some ATF into the cylinders per some threads saying it may help unstick rings and I knew I'd have the car off a few days. Once I put everything back together I proceeded to try and crank for admittedly far too long thinking it wasn't starting due to the ATF. Instead, I had my timing pretty much backwards. Car backfired a few times throughout the cranking, surprised the dipstick didn't go anywhere or anything else.

Thanks for any help

raw oil in cylinders, which then coated all of the exhaust, would probably smoke for a while..

It'll take time to burn off all that ATF (think "Seafoam"). Drive it for a while before giving up hope and doing something drastic.

Does it have a non standard exhaust smell?

Thanks for reading all the way through and calling that out! Didn't think it'd take long - I've accidentally drained my catch can the wrong way but even then it only took ~2 minutes to clear out. I let the car idle probably a total of 30 minutes at a minimum before the smoke finally subsided so that's a wrap with that. To be determined if my valve seals fix my oil issue but glad to have avoided any major issues with this one.