depending on your mileage and wear, anything from 10w30 to 10w40
Remove oil-filler cap and add oil...
The kind that you put in it
Yes you can.
I put 275 25 24 on my 86 box chevy caprice
5W30 weight.
yes
yes I can.
You would probably need to contact a custom oil pan fabricator such as Hamburger or others and have one made.
Yes.
Thru the fuel-filler nozzle...
if it has a 5.7 ltr then yes the bolt patterns for the 5.7 have been the same sense there firt production.
10w30