I got the 500 h.p 383 runs real slow,told him what I was trying to do he said o.k. pay up,I did pay and got junk,leaks,overpriced shipping that was free!! internal issues that Mark was of zero help,I will say never again,for those of you who got lucky,maybe he got a crate engine from G.M.,I would not let mark rebuild my weedwacker,I would rather eat catshi# with a sewing needle than deal with the unanswered phone calls(he doesn't think we know about caller i.d.??) answered everytime before my check cleared.lesson learned,didn't even get the block casting I was promised!!!!!!!!!!!!!!!!