I did this on our ‘78 280Z recently as part of a top end rebuild and refresh.
You could have a go at getting the EGR pipe nut out of the exhaust manifold but you’d want to get some serious heat into it. I just ground off the thin steel pipe down flush with the nut and then drove a short M10 stud down into it and then ground that flush.
I didn’t blank the underside of the inlet manifold when removing the EGR. There is no point as it’s just an empty chamber. I just cut the fitting off.
If you want any specific photos of hoses and connections then let me know. I know there’s a lot going on with the vacuum hoses and it can all be quite daunting