AK already covered this for you, but let me some it up in other words. Dont do a a spacer plate thats the cheap way, get a cool head and get some stroker cut domes for it. Im assuming you meant aggressive trail port, you'll have to get the dimensions on the ports to be able to tell if you can port it for a 4mil. and there is more to it then just droping the ports. What I'd do is call a builder that is experienced with this stuff Jeff at F.A.S.T. and Kevin at Herr Juggs Racing are good joices, my personal preference and who I had do my 4mil set up is Brandon at Wildcard Racing, his number is in my sig. but all 3 are great choices and know what it takes to make a strong 4mil motor