I have a 289 and i just installed a MSD setup a few days ago, I need new spark plugs but i dont know what to get! (size, tip material, heat range??...)
what should i get?

 

If you go to MSD's website, they have a tech forum which you could post to or search for a similar setup to yours. MSD's general guideline seems to be stock plug or one to two heat ranges colder.

For starters, you'll need to get the appropriate size (large for early and smaller for later model)plugs for the head.

 

i just took my old plugs to autozone and the cool owner hooked me up with the exact kind

 

You can't go wrong with the original Motorcraft 42's.

 

I kept the stock plugs and changed the gap to .045" I wouldn't bother with anything aside from the standard ol' coppers. Run for a while before deciding on a heat range change. This is something you can experiment with by reading the plugs, like the spark plug gap.

 

I also changed the plug gap to 0.045 after I installed the Pertronix. Works for me.