Also, Dustin has a proven program for the 496 Procharger combo too and you could keep the 555.

Thanks Alex, this is my buddy's engine I was talking to you about. We found a replacement block, Volvo 496, low hours and great condition. he is thinking of upgrading the lower and going with a MEFI 4 instead of his 555 which was programed for his stock motor but with a Procharger. He is getting parts together so I am sure we will be contacting you in the very near future......