Hi I am new to the site and am hoping you all can help me,

I recently purchased a 1968 Roadrunner. I want to raise the rear a bit higher than stock so I purchased a set of OEM Hemi leaf springs for it. They are not installed yet because now I am hearing from some folks thatb this will not raise the rear at all...Is ths true?? and if so what do I do now, is there still a way to raise it 1-2 inches without adding shackles. Someone said to use blocks but I really don't understansd what they mean by this
Any help will be appreciated..

Problem #2
I am going to buy a set of wheels and tires for it and am thinking about getting some Magnum 500 wheels. What is the widest wheel that I can use on both the front and the rear of the car without risking some scrubbing.
I am thinking about 15 x 10" for the rear and 15x8" for the front, but I am but perplexed about the offset thing etc.
Can someone set me straihgt on this, I need to know exactly what I should buy in terms of size, as large as I can go without risking scrubbing tires. Wheel and tire size please, with the offset measurements if possible.
Much appreciated