Re: E150,E250 and E350 suspension swap
If you just want a bit of height, the springs from the same years are interchangeable for the 3 models. I had a similar problem and instead had my local spring shop add a leaf and re-contour the whole spring pack. Didn't cost much, though I don't remember exactly what it was. HD front springs are available fairly cheaply as well, they can give you an extra couple of inches.
As for the lug change, thats a hub issue so unless you plan on swopping out the rear axle and the both front hubs the only other option I know of is to get adapters. I have seen them online for converting 5 lug to 8 lug.