Help! 1980 450SL - Positive Terminal Connection Under the Hood

Hi all -

I have a 1980 450SL that I'm about to have to tow across the country. The battery is dead (but can be jumped), but I don't want to risk losing the vacuum to the trunk and not being able to get access to the battery to jump it if I need to while on the road.

I understand there is a positive connection under the hood that can be used as a jump point, but I haven't been able to find anything that shows definitively where it is.

Based on what I've read, I THINK it's where I have circled in the attached picture, but I was hoping someone might be able to confirm before I try to jump and end up frying something Can someone please let me know if this is indeed the right spot?

Thanks!
Zack