No problem, it is good to ask questions first. Sorry this ended up a bit long, but seemed necessary. This worked well for me many times. YMMV
I’d use wax and grease remover before wire wheeling and again after wire wheeling.
The engine compartments of mopars have many ripples and waves in the stamped metal. We don’t want to try and fill all of these details, we just want to avoid seeing sand scratches, weld seams, and pinholes from our repairs in the finish, but smoothing It like the outside of the car is not factory.
Do you have filler primer? I can’t read what your products are. I’d not use that on the entire compartment, it will start filling in around bolt heads and tight areas. I would only use filler primer where you did filler work, if necessary. I would use a light coat of sealer on the whole thing before painting. Filler primer is great on the outside where it will be block sanded down. You cant easily block sand filler primer in all the nooks and crannies of an engine compartment.
I would like to see you sand the filler down close with 220. Then finish the sanding of the filler with 400 before applying the primer.
I would recommend sanding with 80-120 on the rough pitted areas that will have filler. Sand the rest of it with 400 grit. I’d skip the 220.
This will make it smoother with less for the primer to fill. Reduces the chances of shrinkage and showing scratches under your paint.
(A friend has his entire 1968 charger body shrink back after painting, now the whole car shines great and shows sand scratches everywhere. It’s really a horrid sight.)
PS: did you get the product information sheet? It says how many coats to apply and how thick it will be, how long to let it before sanding, top coating, etc. you can find it online if needed.