I am new to this forum and was hoping someone may be able to give me their opinion on what heads may be the best choice for my "M" code 1970 mach 1. I am currently running the stock motor and fmx auto. I have a local guy offering me a good set of freshly rebuilt Aussie heads for $1500 bucks ready to bolt on. I could also go with a set of the aftermarket aluminum heads (any recomendations?) and which have better performance characteristics? The car is a cruiser, I am not looking for 11 second times down the track but I would like to see some tire burning performance down low which is what I currently am lacking. I also am wondering if anyone here is using Thorley headers and what pro's and con's I might expect to encounter. Thanks in advance.