bunch of questions

so im building a super budget truck i bought my 86 mazda b2200 for 300$ now i have a bagged 1981 mazda b2000 and i wanna do this truck so i dont rush my 81 as i did before and now have to redo a bunch of stuff to get it to where i want,

now my buddy has a old set of 18inch neeper flys but they are a 4 lug pattern, with a 2inch wide adapter could i run a fwd offset 8inch wide 18 and lay frame with 2wd sheet metal?
then with a 18inch wheel could i lay frame with a 4inch rear z?

I highly doubt it but you need to give us the specs on the wheels. I highly discourage this, 4lug is a downgrade man.

For the rear don't forget to factor in the diameter, and side wall height of the tires you plan to run.

Here are some simple ways to check.

Front:
Bolt one of the wheels on the front, cycle it through travel as though it was bagged and check for clearance. Make sure it has well over 2" before hitting your fender.

Rear:
Decide on what size tires you are going to run. Get the diameter. Example let's say the tires are 25"

Take half of that measurement 25/2 = 12.5"
Now add half of the diameter of your axle housing 2.75/2 + 12.5 = 13.875"

Get the specs on the current tires you are using. Get the diameter. Example let's say the tires are 26"

Take half of that measurement 26/2 = 13"
Now add half of the diameter of your axle housing 2.75/2 + 13 = 14.375"

Next measure the current distance from the bottom of your frame at lowest point to the ground for this example let's say it's 6"

Next measure current distance from the top of the axle housing to the bottom of the frame rail directly above it. Let's say for this example it's only 3"

With all of these calculations here is what you now know
With your current set up you would have to run a 3" rear Z to lay your frame on the ground. Because your new tires in this example are smaller in diameter you will need .5" less of a rear z to lay frame.